I guess it makes sense for elites to be elitist. But there's a point: those who do mileage runs and similar optimization strategies — the famous £2000 BAEC Golds – aren't incurring a huge cost, because, compared to someone who earns status the hard way, they're not using their benefits much.
As for adding a "Blue Metal" requirement, FB has the numbers of how many such elites there are. It's hard for me to imagine there being very many, as A) it's still more advantageous to be in the FFP of the carrier doing the bulk of the lifting and B) their XP scheme heavily favors European travel.
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I welcome the BA refugees, and I've run into them in the wild: they're very eager to explain just why they jumped ship. The lounges have been crowded before they came, and maybe FB will have to tweak its formulae. But I'll also observe that, from my anecdotal perspective, AFKL has load factors that other airlines can be jealous of.
​​​​​Only the very naive don't expect some kind of devaluation of points and an increase in thresholds. But that doesn't mean airlines can be cynical about it.