They totally update every 2-3 weeks; any breaks were intentional (China release, feature packs/season break, holiday events). And within the last season, 2 entirely new zones were released. If anything, the developers are stepping up their game.
The expansion looks awesome, include big updates that players have been asking for, and only the main features have been shown so far. I'd gladly shell out an extra $20-30 for a game that has provided so much gameplay, beautiful graphics, and fun for the original price tag, compared to any subscription MMO out there.
I don't know what players you've been talking to, but even the GW2 subreddit has shown support and hype for the expansion, before and after the PAX expansion confirmation. And there are usually a number of bitter veterns on there.