Does the migration required any user-side action?
I had a seed of ARK wallet written somewhere - should I perform any action, or my funds will be still accessible with this old seed?
Nothing needs to be done from user, user shouldn't experience any difference when interacting with Ark blockchain all of this happened in the "back" with the ones who are running the network (delegates).
And what are the actual reason for migration? Understandable for common people

(I am sorry, but I haven't really understood the last update in details.)
Is it easier to develop and to program on typewrite or something like that?