as it will null the need for Barrows gloves and therefore the entire RFD quest
Avernic Defender didn't null the need for Dragon Defender. Make it an attachment on it if needed, though I think it's a silly trend. If an item better than barrows gloves comes out, it will most likely cost 50m or more, plenty of people will still use B gloves.
RFD also isn't really a hard quest, it's a major mark on the account for mid-high level tier, but it's still not even a grandmaster quest, devaluing it's reward wouldn't be a big deal.
If better gloves were implemented, they could just go the zenyte jewellery way, making them not hybrid gloves or offering another "con" to make them not strictly better.