Especially since there was NO reason to do it, they even apparently had a module that connect to stopforumspam set up in one of the betas or RCs...! but that's the way it goes with a lot of these companies, they start out nice and providing good service for a fair price, and get greedy. Enterprise customers don't care about price tags - indeed, they want to spend as much as possible - and so prices skyrocket. I've seen it happen way too many times, including one piece of software whose price started out at $150, doubled with every new version, and ended up jumping from $600 to $15,000 ... and setting up a service to compete with their former buyers.
Not saying IPB's going that way but once you're enmeshed in there, with all their services and features, it's hard to get out. To be fair they haven't pulled the usual trick, which is to change the name of the product and claim that perpetual/lifetime licenses are invalid because it's a Whole New Thing. And they are still honoring their old commitments.
I do wish they'd spend more time on optimization and less on ancillary features, and make some attempts not to destroy all skins and modules with each new version. Making it easier to relogo would be nice, too - not everyone can do a simple white-on-blue.