It might be a nuisance for you - but ultimately, you can't really blame PTC (and other software houses, for that matter), for introducing measures to prevent unauthorised copying and distribution of software. Otherwise, there would be nothing to prevnet 10 (or more!) users clubbing together, to buy a single copy, and share it between themselves. (I know this is in fact common practice - but that doesn't make it right!)
The need to have the CD in the drive is documented on the purchase web site, so you also can't claim you didn't know about this requirement.
And, does it REALLY drain battery life significantly? On my PC (not a laptop, admittedly), it only accesses the CD-ROM drive very intemittently - most of the time, the CD-ROM light is off.
I have tried Virtual CD and it seems to work well. The only issue I had with it is that it seems that the virtual drive letter needs to come before the actual CD drive letter. I had to increase the drive letter of my actual CD drive(D: to E. The old letter (D was then given to the virtual drive. Other than that, it works great.
It is very convenient especially if you also want to listen to a CD while using Pro/E. And now I don't have to worry about losing the Pro/E CD either.