I honestly think of USDT when I go to the P2P exchange. If I was given a choice between Bitcoin and USDT, without hesitation I would choose Bitcoin. But as OP says, traders wait for the bitcoin price to drop to buy more with their USDT pair. Without Bitcoin in the crypto market it would not be as we know it. All other coins depend a lot on the address where bitcoin is moving.
Yes all other altcoins are very dependent on the price of bitcoin.
Because without bitcoin in the market like there is no power and so is USDT.
Markets without USDT I feel like gravy without salt that's its nature.
So for me Bitcoin and USDT are still important and it's hard to choose between the two.