I think the expectation is that bluetooth is either always on if you use it, or always off if you don't. You would only need to switch it occasionally if things aren't working right and you want to switch it off and back on.
Bluetooth is not hazardous to your health. I know you disagree, but it's not.
Bluetooth is not a significant power drain unless you are actively using it. Of course, if you're on a call, your cell signal is using far more power than bluetooth. Having bluetooth on does use some power, but it's just not that much power.
Just today I unplugged my phone at 7:00am, I was out all day taking photos (using screen-power and processing-power) and I got a low-battery warning at 9:00pm. Bluetooth was on the whole time (and I was using a bluetooth speaker to listen to music until I left my house around 8:00am).
Of course, anecdotal evidence is just that, and it is difficult to compare usage situations, but I think 14 hours of all sorts of activity, WiFi, photography, etc. and blutooth on top of it is pretty good. If your battery isn't holding up, it's something other than bluetooth. Turning bluetooth off would just be a bandaid. You should find the root of the problem and fix that, rather than trying to squeeze battery time from bluetooth.
So to return to my first point, I think bluetooth is just intended to be left on. I know it's not a solution to the problem, but at least it's an explanation. Perhaps a future software/hardware update will change this and make it easier to switch on/off, but for now it's just four taps. If you want it to change, you can always add your vote with the appropriate feedback form that Apple provides.
I haven't tried this myself, but this app claims to switch bluetooth on/off, and (obvioulsy) it would be on your home screen.
There is another similar app that doesn't work in iOS 5 and I think would just turn Bluetooth on. This one doesn't mention any such limitations in the decription or the user reviews.
Might be worth a shot!