Problem, of course, is not the bolster itself, but the amount of maths/tests you have to do to actually get the optimal result... the whole thing looks like a typical, sloppily coded another layer added on top of the system probably to reduce the work effort required to implement it. I agree with one of the posts above, that first introducting expertise to make people grind pvp gear for pvp, and then bolstering the pve gear defeats the purpose of the former. Sadly, the game is not this golden egg laying $100m world-changing project it was at release, so I guess we have to live with it.
Of course, it could be argued that there are super simple bolster systems in other games, that don't cause your brain to overload, and do the job just as well. Like the simplest one:
For Each Gear Piece Worn
{
Has Expertise? Leave as it is for calculations.
No Expertise? Use the lowest pvp piece (recruit-like) for calculations.
}
Fixed.