Why bitcoin should not support pre-mined tokens or ICO use cases, better than other coins. If projects are legit then what would be the problem ?
Take a look to Komodo solution for example...
Because people don't want it. If there was enough support somebody would start to develop a solution but it's not happening because we don't need it. Altcoin markets are chaotic and premined tokens are usually scams or shitcoins like ripple. I wouldn't want bitcoin to turn into this.