In my opinion, the best changes are those that won't actually make Game Maker less powerful. If you make Game Maker less powerful by adding some annoying limitation, part of the Lite users will buy Pro/Standard, but another part will stop using Game Maker in favor of some other game development platform, or simply stop making games altogether. That's definitely not what you want. Don't forget there are free alternatives (e.g. Construct).
EDIT: Also, you don't want GM8.1 Lite to be less powerful than GM8.0 Lite. Especially if you're going to stop supporting GM8.0.
Edited by Maarten Baert, 01 April 2011 - 11:38 AM.