Would also be nice if some enterprising Wiki-er could rebuild battery packs for rechgargeable handtools.
I've done this many times, biggest problem is that most of them have NICADS in them which inherently have problems because of there memory effect. Often the packs are fast-charged but without proper thermal protection which means some cells get too hot and are destroyed. The batteries are connected in series and hence charged in series, any imbalance in one cell will magnify the memory effect problems.
If you replace them with NiMH batteries they are easily destroyed as well because they are very intolerant to overcharging at faster charge rates.
The real answer would be that manufacturers revert back to using standard generic cells that can be charged and tested individually - but of course that would reduce their re-sell rate enormously.