Also those add-on developers should be reminded that we already have a system they can use called the asset uploader. All they need to do is add a specific field to a template and this will allow files their add-on uses to be uploaded.This would be a welcome feature. +1 vote from me as well. Some modifications require you to upload files to the server and it would be handy for those. Sometimes it's a PITA to SFTP the files to the server and something built in would be quick and easy.
A bit like we have for a bunch of our style properties. No real reason an add-on dev can’t be providing access to that for most files.
But, again, if it’s not image files, then you probably need SFTP anyway.