I've been using it for about ten years... I grew up with it, you could say. Is it the only option? No. Does it do more than any other program? No. Is it able to do everything I could possibly want? No. Reaper has about 200 more options than Pro Tools, and does things I never even dreamed of doing. BUT... Pro Tools to me is like I want Microsoft Word to be. It has a simple, powerful workflow, it gives me all the features I want, and it is stable. Reaper is like Microsoft Word in the 2003 incarnation... every option under the frigging sun, at the price of simplified workflow. And not as stable. At least, in my experience. I realize you posted about audition, and I have no experience at all with Audition, the last time I used that, it was Cool Edit. But in my experience so far, Pro Tools is as stable as I could want, does everything I want it to, and does it all in a way that just makes sense to me. Especially when I compare the workflow to an analog, mixing board + machine style of working.
Now, that said, I have to take issue with some of your post information.
Pro Tools LE is NOT the most expensive DAW. It's actually pretty cheap... considering that it is included in the cost of the hardware, and the hardware is not all that much more expensive than other hardware from other manufacturers. An Mbox costs $300, which is like buying the software for the price of most other DAWs, and getting the hardware free.
And if you run it on M-Audio hardware, it costs you $250. Hell, that's $100 cheaper than Audition! That's certainly competitive with everything out there... only Tracktion and Reaper are significantly cheaper.