The advantage of a multi-hit move being harder to dodge lessens since people will time their dodges more properly in high level play, whatever that means.In a high level of play, Single hit moves also lose the substance of their strength on Multihit moves. Being harder to DI matters much less since everyone at a high level can DI them just as well.
At any rate, easy DI opportunities are actually much less then you think they are in this game because of lolhitlag.