I think it has got easier but it's probably more down to skill of the player than to how updates have effected the difficulty, having said this I only began playing in .17, it took me a good few months to be able to do a 3 Kerbal Mission to the Mun, I could do a one manned mission easily, in fact i'd gotten to Duna before I could land 3 Kerbals on the Mun haha So i'd say down to skill of player and how ambitious the thing is you're trying to land.