Please borrow a scheme from D&D Beyond and have P2W Feats
Yes, these unlockable feats must be purchased through one or more of the following
1) 500+ DDO point purchase
2) VIP subscription or season pass
3) Expansion purchase
4) Bundled offer
Make these Pay to Win Feats extra special and more powerful than the standard free feats you can choose from at character creation. Better than Toughness, better than Improved Critical, better than Quicken and Maximize.
You might also consider adding pay to win skills and spells next but one step (or P2W feature) at a time!
Yes, I was playing around with D & D Beyond's character generator for the first time and ran into the "issue" of only having one free feat available to pick: Grappler. This immediately turned me off and made me quit the character generator. Theirs is a very poor implementation of P2W feats. No variety of free feats at all.
P2W Feats should work fine for DDO because there is already a vast number of good free feats the masses won't be too upset for the special P2W Feats that get added next.