Were you on the AOS dev team?
Bad idea. Really bad.
The game does need gold sinks, but a tax wouldn't work. Penalizing success usually has the opposite effect of the one that is intended. What the game needs is a way for people who don't have the billion gold to compete in both PvP and PvM combat on an equal footing, while retaining a lot of non-combat benefits for the players who do. Imbuing is helping to fill that role nicely.
Being rich should mean that you get the big house, the nice stuff, etc. but you don't get to go into god mode in combat; the poorest players out there, who had good skills, were able to fight and win in both PvP and PvM pre-AOS. When AOS turned the game into an item-based system instead of skill-based, it turned everything on its head. For the first half of UO's history, a full suit of valorite armor with a katana and shield were maybe 20k gold. Maybe 10k for leather for a mage. Decent combat equipment was cheap. Even a week-old player could buy a good suit of armor. A rare item to put in your house and show off to your friends might bring millions, even though it had no use in combat.
Now, if you don't have several hundred million gold worth of equipment, you had just as well forget about PvP. And only the people with that uber suit can make the gold and get the artifacts they need to even do PvM effectively.
When gold didn't matter for combat, whether people amassed ungodly amounts of it or not wasn't all that important. It might buy you some neat junk to show off, but it wouldn't make you a great warrior or mage. That took skill and experience. The AOS crew made skill and experience close to irrelevant. If you don't have a skill, just grab some jewelry and artifacts and you have an instant skill. If you want stealth, for instance, a +20 cloak, +10 robe, +10 bandana, +20 leggings, and two pieces of +15 jewelry, and you're at 90, with 0 real skill. Why even bother training the skill at all?