Problem is thats what players are afraid of. That a new player can just come into the game and buy all the skills from day one. Not only new players, but long term players can just make new accounts, buy sp on the first day and fit them into titans. Give it enough time and you'll see even more titan-fest in fleet battles... like its not boring enough.
If you want to Buy things to do well in a game, go play Entropia Universe. At least you can withdraw your cash out of that game as real money.
The big problem is that if they start selling guns, ammo, ships, or whatever other items will ruin the market. Little in this game is just created from thin air. Almost everything needs to be built, mined, ratted, or whatever. Even when selling a PLEX that isk doesn't come from thin air. It had to be earned by someone. Allowing people to buy stuff in MTs takes that out completely.