Hive has come a long way, the pair hive/usdt is listed on many exchanges, I prefer this method because I can set the exchange price for euro/usdt and then usdt/hive, if you buy directly you'll end up with a bit less than if you do it this way. This is not so important if you buy a small amount but the differences are easily visible for higher amounts.
My guess is that many people who use hive, there's a big chance they have a Binance account as well, if not, it's more useful to do a kyc with Binance and then use them for different trades as well than to do the kyc with Transak.
The direct option to get hive could be nice for newcomers but the thing that they have to do a kyc doesn't look too appetizing.