It is true that smart is a player that would help them on defense, and on offense they have enough players so they do not need another offensive guy. They already have what they need and because of that they should not really focus on whatever they lack, and that is defense. If they could also get a decent big, who can grab boards and protect inside, then they are going to be contenders for sure.
However, so far they are not doing that great on that part, and that is going to cost them a ton. Hayes isn't enough, they need someone who is much better there, I am not saying go get AD back, but they need someone who could be good enough and be playoff level player at least, otherwise they are not going to get any good results.
Smart is there for defense not offense so its okay, also its the same position for him when he is on boston, you are correct when you said they need someone like ad caliber, but currently they got the multiverse version of AD, ayton probably will show some brilliance if he can adapt with luka, but if there is going to be drama like what he did in suns, that would be another problem, adding to the lebron management issue, which we are still waiting what will happen, although were not sure if they are going to trade lebron and focus on luka and lakers future.