Don Durito
Hero
Thunderwave is a first level spell, which means
1. The wizard has to have it prepared
2. They can only do it a limited number of times per day.
3. There may be better uses of their 1st level spell slots.
4. Thunderwave makes a very loud noise within 300', which will likely alert monsters.
Meanwhile a fighter can shove people around at will and do it more efficiently and with less consequences.
The point of spells is that they can be "I Win" buttons in very specific situations. But there are (or at least, there should be) consequences. If the consequences aren't severe enough for the effect of the spell, then it's a design issue.
Yes but something that is impressive once is generally better than something you can do many times to little great effect.
You may only need it once. Forced movement is most useful (and satisfying) when the terrain is in the right conditions. For example, someone has cast a wall of fire and you want to shove someone right through it.
Pushing one person doesn't reshape the battlefield. The ability to do this is something Fighters in 5E really lack. Plus unless you choose a particular weapon set-up and a particular feat you have to give up an attack - which is rarely worth it. So you aren't going to be pushing people every round - even if you can.
Not to mention that if you choose it as a Sorcerer or a Bard you can cast it as many times as you have 1st level slots - which will almost certainly be more times than you wish to use it.
I picked Thunderwave as an example because it's really not beyond the bounds of what 4E Fighters could fairly routinely do.