HOTS isn't without flaws, and that was never said. However; HOTS is still in open beta. The point of this time is to figure out which of those is particularly problematic and deal with them. LoL on the other hand is extremely well established and is making good money but refuses to look into expanding like many players wish. It doesn't need to have a map for every champion. Heck, it doesn't need a map for every nation. Just some variety. Currently ARAM is my most played mode, because I never know what's going to pop up.
It was also noted that HOTS was not likely to take the competitive players away from LoL. It would take the casual players away. It currently has enough champions to provide a good bit of variety in roles and play styles, and the variety of maps even makes it worth learning multiple styles for each champion because a tanky fighter might be more appropriate on maps where you need to defend objectives compared a damaging fighter on a map where killing certain mobs is the goal.
The point is that HOTS is likely to take a number of the players that have been crying out for new maps away from LoL, and if Riot wants to stop it that drain on their player base then they'll have to adapt in some way. Personally, I'd like a set of rotating maps/modes in addition the permanent few we currently have.
On a side note, I don't like any of the games that they draw their heroes from and I've greatly enjoyed HOTS.