Is that what he wrote, or what you read?
-O
Judging by some of the comments on the now-locked thread, a lot of people seem to have read that, or similar. I'm one to agree, even if it's not indicative of any sort of trend with the game, to have someone who is the lead designer for the game basically say they enjoyed the game when the rules were utter garbage is a little frightening, more so because he didn't mention anything about what was
wrong about that style; it indicates (or hints at, at least) that he might not KNOW what was wrong about that style and therefore be incapable of making sure that 4e and future editions don't go that route as well (and based on the response to things like Cleric nerfs and the Vampire class, it might have started down that path already).
To put it in perspective: I am a software developer by trade. If the CIO of my company says that he enjoyed programming the most when it was in COBOL on a mainframe, because it was harder to do than it is to write C# with Visual Studio on Windows 7, it's a fearful prospect because it indicates a complete lack of evolution and understanding of better things. That's a similar situation here with Mearles - he is basically saying "I had fun when I had to think creatively to get around shoddy rules", but he's making it sound like the shoddy rules were not a problem that shouldn't have existed in the first place.
If he had said basically,
The old rules weren't balanced at all and the Thief class was way underpowered, so I had to resort to being creative to get around the bad rules it would have been better received because it at least indicates an acceptance that the old style was
bad compared to the new way things are going. Instead, he basically said
I had a lot of fun playing an underpowered class because it was underpowered so I couldn't use the rules to my advantage, which isn't acknowledging anything except the fact that he doesn't mind lousy rules (or worse still, cannot determine if rules are lousy) and, it could be inferred, prefers them
because they fostered creativity as a workaround.