Since you guys are too dim to see it, let me put this in a way you'll understand.

Imagine your suit is a pair of shorts. Your fitting skills are the pockets on those shorts. Your modules and weapons are what you put into those pockets. As you progress from basic to proto, your shorts get longer, and your pockets get longer. You can also independently increase the length of your pockets by increasing the fitting skills themselves.

So, in the worst plan ever, you spend your points to increase your fitting skills, giving you really deep pockets. But you don't have any modules or weapons better than militia or basic to put into these pockets, and because your shorts are still basic, your pockets flap idiotically past the hem of your shorts. You have ended up sinking a huge amount of points into something that isn't of any immediate benefit to you. Proto players with longer shorts and deep pockets filled with proto goodies laugh and jeer at you, and still kill you in two hits. Eventually you get bored and give up this game because the gap between you and them is too huge. Doesn't make for long player retention, now does it?

Now the question becomes, what did you do wrong? Simply put, you prioritized numerical, passive stats over actual content. The ability to fit better modules and weapons means nothing if you don't have access to those modules and weapons to begin with. The best course of action, if you are spreadsheet-minded, is to use hydraSlav's fitting tool to design the ultimate fit that you want to use at proto level. Then backwards engineer your advanced and basic fits, along with modules and weapons, and the skills you need to unlock to access them (including fitting skills) so you have a solid plan of what needs to be unlocked and in what order. This will get you more content and actually make the game entertaining (as you will somewhat competitive) instead of having to grind millions of skillpoints while running militia fits, to no apparent reward.

Fitting skills are important to unlock as you progress with unlocking modules and your suit. You should not prioritize getting CPU/PG to Level 5 before getting modules to advanced or proto, or even your proto suit. In many cases, you can get by with the proto suit and proto modules without having all fitting skills maxed.