From a development standpoint it likely was. Doing a plug-in rewrite is a ton of work.
I understand software development isn't cheap but it's kind of annoying that $60 doesn't include free upgrades.
Expiration Date
Licenses purchased for Sublime Text 3 do not expire, however
an upgrade fee will be required for Sublime Text 4.
From: http://www.sublimetext.com/sales_faqYeah, they do. It's very hard to do in both cases, for different reasons - licensing for Emacs, code quality/style for Vim - but it happens. For Emacs just read this: http://www.gnu.org/software/emacs/manual/html_node/emacs/Ant... and this: http://www.gnu.org/software/emacs/manual/html_node/elisp/Ant... (or look at normal changelog, but I kind of like this "backwards in time" format, it's fun :)) to get a feeling for what you'd miss by not doing a "major upgrade".
Anyways, theres no satisfying HN. When Atom came out, the consensus was that they should've come out and said it was an ST clone upfront. Now someone does that and it seems the tide has changed.
While we're on Atom, since switching I've found its everything ST should've been. Its open source and has a huge community developing very useful plugins (not to mention, they're well integrated from a usability perspective - git/terminal status/linter/etc). Also, I have yet to run into a serious bug/versioning issue which ST plugins were rife with before I dropped it.
Not that it matters much, but it's actually $70 now: http://www.sublimetext.com/buy
They did announced something recently, like getting ready for ST 4. And 3 is not even a major upgrade from ST2, IMHO.