The attractiveness of wallets such as Trust Wallet is all in the fact that they support altcoins and sometimes people seek a light wallet to store their shitcoins that is not their centralize [custodial] exchange account. There is also the advertisement by the company behind this closed source wallet that would attract unaware newcomers to a very risky and insecure wallet.
The popularity is definitely not that high though because sooner or later everyone realizes this is closed source and they should stay away which means they lose many users too.