While I am not a fan of the transaction based BGS, switching it to value based is likely to lead to the same sort of exploitation that the Powerplay players currently complain about.
It's extremely easy to afk-farm bonds and bounties at the moment. My corvette can survive for over an hour on it's own in a HazRes or CZ without losing it's shields. As part of a wing, I could leave it 24/7 in a RES or CZ and only return once per day to hand in the accrued bounties or bonds.
I'm not saying that this means that value-based is a bad idea per-se, I'm just saying that while afk-farming methods remain easy, switching to value-based BGS has a glaring and obvious problem that would need to be addressed first.
Personally, I'd prefer to see a mixed value/transaction system.
That just means ENG's are ridiculously OP and they're an exploit in themselves. So in fact, you mean ENG needs fixing.