Well, in all honesty, the iPhone isn't meant to be a business phone. This is why there is no business plan through AT&T. This is exactly why the phone is missing some of these features. It's simplicity is what makes it appealing to the general public. I know you think it's just a simple missing element, but there's NO way to make everyone happy. For me, MMS is the one thing I miss the most on the iPhone, and I'd take that (and about 10 other missing features) over a missed message light or beep any day.
It is certainly interesting to see what features are important to different people. Things that are a big deal for some seem to be no big deal to others.
The missed call tone is not a business feature, it is something that exists in even the cheapest free phones you get from other carriers. Interesting that we have VPN support (which is certainly geared toward business users), but not other more basic features.
In my case, I use my iPhone only for personal use. However, it is my primary phone, and since it is so easy to miss a call, I find it frustrating to find out that I missed a call hours after it came in.
I think it comes down to how you use your phone. If you receive important calls (ie kids, family emergencies, etc), then you don't want to miss those calls. If you use your cell phone as a backup to your land line, then maybe it is no big deal.
Call this personal preference if you want - thats why we have options to turn these things off.
One nice feature of the iPhone for me, is that these types of things can be fixed with a software option that won't increase the complexity of the phone, and will give some of us back the features we had on our old phones...
I can't wait to see what version 1.01 of the iPhone software has in store for us...