Proposal: when I already some games that is part of a bundle, I should be able to purchase the rest of the bundle at the same discount as the whole bundle, without re-purchasing games that I already own.  I think GOG already does this.

Example: let's say games A, B, C, and D are part of a bundle.  Each game individually costs $10, but the bundle is discounted 50%, so the entire bundle only costs $20.  I already own games A and B because I purchased them individually.  If I try to buy the bundle, it should cost me $10 because I am only receiving two of the games, C and D.  (Note that I spent a total of $30 on the games in the bundle, which is still more than the cost of the bundle.)

Rationale: the current system is set up to "punish" customers who purchase games individually by making them ineligible for future discounts from bundles.  I don't like this as a customer, but more importantly, I don't like this as a developer.  Enticing new customers with a bundle sale is well and all, but I think existing customers should be eligible for the same discount.   Customer loyalty should be rewarded, not punished.