I think you're right that everyone shouldn't be charged because Marco and others think the product is worth it. Some bought it on the promise of a free upgrade.
An upgrade to version 2 wasn't part of the "value" I attributed to TM when I bought it years ago, so were it not free, I'd seriously consider buying anyway (even though I do little coding nowadays, and am impressed with SublimeText2).
So, count me as mixed on the whole thing. I wouldn't balk at a nominal upgrade fee, and don't begrudge those who want to pay more, but sympathize with those who bought on the promise of an upgrade years ago.