Avtur.
I agree with you to an extent. The problem is that that could look like an attractive cost cutting exercise and lead to pay cuts. I don't necessarily think the ground trades should earn less (although I think some of them are overpaid for their role they still have an important job to do) I just think that individuals who do the most demanding jobs should be appropriately remunerated.
Please bear in mind that I am a FJ pilot so my posts will always have that slant attached. It doesn't mean I don't care about everyone else it's just that it's not my milieux.
On a separate note if someone were to suggest flying pay on days you fly then I would suggest they need to decide upon what it is for. If it is flying pay then it should be payable from day one whenever you fly. If it is RRP then it needs to be paid regardless of your current role. Due to this contradiction I don't think that will happen. Otherwise, as has been pointed out, taking a ground job would incur a financial penalty which would be counter productive to say the least.
BV