First off, compared to at least ONE phone (the moto droid) the Hero isn't lesser specced, they both have 550Mhz CPUs. so if the droid can run it why not the hero. Second, HTC has said there will be an update, they just wont say when or which version. But considering 1.6 is now obsolete, and they aren't talking about an update till the new year...do the math.
Then you have the issue of 2.0, by every account thus far, running MUCH faster on almost identical hardware and the "not beefy enough to run it" speculation seems pretty flat.
As for why bothering if HTC added most of 2.0s features in, well, couple reasons. They may have added the functionality, but not the speed. So for that reason alone I'd like to see it. Second if they can update 1.5 to be almost as good as 2.0...wonder what they could make out of 2.0? All the integration stuff they added (that one person here complained about how confusing it can be) is all API based in 2.0, meaning they could, by all accounts, do what they already did with 1.5 1/2 and do it BETTER, or expand upon it.
Everyone just needs to take a deep breath and remember that HTC has a LONG history of providing significant upgrades to WinMo phones WELL after they were released, and that's an OS they have to pay for!
Breath deep and relax kids. Get to know your phone and have fun, and before you know it we'll all have a 2.0 build to slap on our phones.