Useless upgrades?

This is for BTD5, BTD Battles and Bloons Monkey City.

So, there are some upgrades, for example Technological Terror on the Super Monkey, that seem the same at 0/4, 1/4 and 2/4 upgrade layouts.

Usually I upgrade first to Plasma Blasts and then to Technological Terror, but is it the same if I upgrade only the 2nd path? Does it have to do anything with popping power or something? Or is it just a waste of money?

This goes also for Ray Of Doom on the Dartling Gun, and maybe some other towers I forgot to mention, but these are towers that I actually use, so that will do.

So, do these upgrades that seem useless at first affect attack speed, popping power or something like that?

I can assure you that a 2|4 Technological Terror is stronger than a 0|4. The left sided upgrades will affect its popping power no matter what.

Same goes for the Ray Of Doom. A 4|0 Ray Of Doom can't and will not pop all bloons. A Ray Of Doom cannot pop lead bloons if it does not have the Depleted Bloontonium Darts upgrade on the right side.

Every upgrade that seems useless has some use of some sort.