We would like to be able to create an SPFx form and associate it with the List/Content type Disp, Edit, New form so that no matter how a user finds a list item (search, OOB list view, custom list view, etc) they see our custom form. Currently our only option is to create a completely disconnected experience in which we write a custom list view that points to custom form pages.

Alternatively support field customizers with edit model to enable custom field editing experience.

The latest adjustments in the Microsoft Store police allows store's add-in to works with conjunction with another add-in that is available only from the provider. The solution package (.sppkg) build with SharePoint framework is not classified as 'add-in'. Thus, we cannot add add-in in the Store that depend on SPFx solution and there is no way of delivering customizations to the modern page.
I can offered two options for solving this issue: 1) Adjustment of point 4.18 (https://docs.microsoft.com/en-us/office/dev/store/validation-policies#bk_4) from the Store policy to allows SPFx modifications 2) ApPSource store to start allowing .sppkg solution packages to be added

Please provide subscriptions API (_api/Web/Lists('listID')/subscriptions support (WebHooks)) SharePoint 2016 On-Premise which helps in webhooks, desktop notifications, mobile/push notifications and cross platform notifications to name a few.

App-only policy in the SharePoint App Model is very restricted regarding Taxonomy operations. Even if an app is granted full control over the tenant, it lacks the permission to do anything but read operations on Taxonomy. Please provide the ability to create Groups, Term Sets and terms using app-only policy.

Please provide a well-known placeholder for the property pane or better a similar placeholder that let us create a sidebar.

Having this ability would let us create powerful sidebars/toolbox extensions. This would be a super cool enhancement!

Right now there is no clear statement regarding the supportability of IE with SPFx. Since IE 11 is still supported for O365 and SharePoint Online, customers assume that it is supported with IE as well.
Currently SPFx is impossible to use with IE because of performance issues and very bad memory leaks in IE. The more content and web parts are on a modern page the worse it gets. Thus, I suggest that you either fix those issues, or make a clear statement that SPFx is not supported with IE anymore. This would really help customers in making their decisions.

Provide option to enable\disable event firing from Remote Event Receivers in SharePoint Online (CSOM/API) similar to SSOM - EventFiringEnabled

Actually, the only way to paginate list items using the new REST APIs is to use __next property. There's no way to have a full working pagination using $top and $skip token as for any other REST call.
See my comment here:
http://msdn.microsoft.com/library/d4b5c277-ed50-420c-8a9b-860342284b72.aspx

It is actually possible to import the definition of a XsltListViewWebPart via LimitedWebPartManager in CSOM. However, not all properties are supported. Important properties like XmlDefinition, Toolbar, ViewStyle, .. are being ignored. There's no possibility to have everything set correctly not even manipulating the backed view after importing the WebPart. Please read also this discussion:
http://sharepoint.stackexchange.com/questions/90433/add-document-library-xsltlistviewwebpart-using-csom-or-web-services

It would be great if we are able to use font icons instead of url to images for Command Set extensions buttons icons.
This allow 3d party extensions look more aligned with 1st party (same style, same icon color)

Provide a SharePoint Framework mechanism/API that allows for Site or Site Collection Read/Write of Key/Value pair properties for use in SPFx related configuration and customizations. Similar to how the property bag was used in classic.

One use case is for storing configurable properties or even user personalization configurations written and read by an SPFx solution.

This is one of many uses cases that would make this feature valuable, so in addition to your vote, please feel free to comment with additional ways in which this feature could provide additional value.

There is currently no good way to do enterprise level automated deployments of an SPFX addin into a SharePoint 2016 on Premise environment..

Consider a case where there are 1000 site collections and we would need to deploy an SPFX app to all sites automatically. Currently there is no way to perform this deployment in an automated fashion. It is not possible through powershell, csom, c# or in an administrative UI.

Having this ability would solve a large hole in capabilities with SharePoint Framework

Provide a way to get data about all components that present on page in ApplicationCustomizer like SearchBox, Search, Documents Library, Lists, Navigation bar etc.

The idea is to have full control on user interaction with components.

In example I want to make an additional action when user clicks on folder, file, list item, navigation item, search result item etc...

Ideally to have access to domElement and data model of component.

When creating Site Collections through CSOM and providing an LCID. (For example 2067) an exception is thrown.

[Quote]
SiteCreationProperties.Template\r\nParameter name: Specified value is not supported for the SiteCreationProperties.Template parameter." is thrown at ExecuteQuery();
[/Quote]

The Exception is also not pointing in the right direction.
1) It should be possible to create Site Collections providing the LCID
2) When an Invalid Lcid is passed, the exception should point in the right direction.

List items that have an Audience field attached should be audience filtered when retrieved via the REST API.

For example, a list that has link items with the Audience field attached to target particular items at particular groups of people. If the REST APIs are used to retrieve items from this list, then the identity of the requesting user should be optionally used to filter the results based on audience.

Right now there is no API to check that. If you add a security group into a SharePoint group, there is no way to check if the current user is a part of the SharePoint group: The user is not listed in the group.Users and the SharePoint group is not listed in the user.Groups. The 3 APIs that allowed to do this in full trust code are missing from CSOM so we need an alternative.