I get what you mean about the whole performance issues and stuff Sam, and herein lies my dilemma...
I am very satisfied with my phone. Simple. I jailbroke my pervious iPhones because they didn't allow me to do simple things like change the wallpaper or icons (urgh... definitely don't miss those days!) But now, I like the way my phone performs, I can customise how it looks and it's very stable. What does rooting actually give me that I really need and don't already have? Before 2.2 I was really bummed out about not having apps2sd sure, but now I have froyo so that's been made redundant. The only thing I am a little jealous of is some of the cool battery icons, you know the circular ones with the percentage in the middle - so cool, but that's it. That's literally all I can think of that would make me want to root my phone.
Can someone convince me otherwise??
Although google's implementation of a2sd is based on the same premise, its no where near as good as a2sd+. Froyo lets you (if the developer coded it) to move part of the app onto SD card.
a2sd+ makes your phone think your SD card is internal memory. It also has the dalvik cache there. In short more of the app is on the sd card and ALL apps are there. There are no problems with widgets etc being installed on the SD card (unlike a2sd). The actual internal memory fills up slower with the rooted version, so you can install more.
You can control your battery better by underclocking the CPU, or undervolting it at the same clock speed, getting much better battery life.
You can even overclock it so it performs better. Download quadrant and get a speed for your phone. Then compare it to a rooted version, you'd be amazed.
Also, you can remove system apps. You can get rid of stuff on your phone that you never use.
You can use proxy with wifi with some of the custom roms.
Generally the roms are more stable, bug fixes to fix bugs that HTC haven't. Plus you can have massive amounts of customisation over what you had before aesthetically.
You can manage memory better. You can limit the amount of apps that run in the background. You can even prevent certain apps from listening to certain events, improving battery even further.
There are so many things. It basically gives you the access to your phone that you should have had out of the box.
Rooting is not for everyone. It is for me though cause I'm an IT geek.