No skill is useless indeed, they all do something. Some of them just do it way better than others.
You are an optimistic person are you not :p ?
Breathing bubble/Mass breathing bubble ==> Do you really have issues again clouds ?
Erratic wisp ==> Do you like being teleported right in a pack of enemies ?
Turn to oil, bleed fire, dimensional bolt, planar gateway, ... the list is so long I don't even want to list them all again. Have a look at the survey, a lot of people highly disagree with you.
Even some good skills (like uncanny evasion) are completely outshined by others (like chameleon cloak).
If you answer the survey you will be able to see the rating for each skill. You will find that Uncanny evasion is in fact a good skill. Being outshined by other skills does not make a good skill a bad one.
So if you are replaying the game or just a "theorycrafter" right from the beginning, you will only use a small portion of all skills, because you only have a few AP per turns and putting point in Memory is costly.
This is not about theorycrafting but more about liberties of character creation. One of the strongest point of DOS is being able to create your character as you feel. But with many useless skills, a lot of hybrid class cannot come to life. If those skills would become relevant, it would change a lot of things.
