Why does Krang need scientists?
 

I always found it weird that he tried to get rid of Baxter but sometimes he sought out inventions made by other scientists or look for scientists to have work for him like in Attack of The Neutrinos.

But why is that? Krang is already world's above any scientist, including Shredder. A lot of the inventions he'd sought out is something that he could make if he's smart enough to design a mobile fortress with a force field that can shrug off army artillery, trans dimensional portals, and cyborgs as well as chemicals to make mutants. I just find it strange that he'd need anyone's help or try to find inventions he could easily make himself since he's much smarter than any human.

interesting thought
 

In general it's always good to have different perspective on things. A bunch of superior minds together in one room would certainly cause some animosity due to alpha behavior. All that said having different perspectives bring out things you haven't thought of.

For example, one scientist might be infirior in intellect to Krang but he could say "what if we use it like this" (referring to an invention of course) or something along those lines. Krang certainly would have the intellect to have thought of it himself, but it's good to have someone bring it to his attention sooner.

It's really Krang venturing into every way possible to destroy the turtles & take over the world.

Being a genius doesn't mean every idea's gonna come to you. Sometimes you need another genius' insight, other times they've beaten you to the punch on certain tech. Makes sense.

Alternately, the short answer is "It's a cartoon". :trazz:

Strange he got rid of Baxter. I know Baxter failed but he was a brilliant scientist. He also didn't fail nearly as many times as bebop and rocksteady.

Maybe Krang was like the Steve Jobs of Dimension X.

The only logical explanation I can think of is that Krang's genius may not necessarily apply in this dimension, so what works in Dimension X won't always translate into this one.
Otherwise, there would be little to stop a complete and almost immediate takeover of Earth by the Krang within a matter of days or weeks.
A handful of funny-looking green dudes armed with sticks and knives certainly couldn't do anything about it and Earthling scientists would be superfluous, primitive idiots to the Krang.

He cant pick **** up with his little t-rex tentacle arms.

Because he's not from our dimension, so naturally he'd need help in finding out how things work on Earth. That's where scientists come in.

Human Baxter Stockman had great potentials. Imagine if he took a false indentity (since he became known when the police arrested him after the mouser robots were defeated by the turtles), but still scientist/inventor, to go undercover working with other scientists and inventors, participating in research at laboratories and universities, and steal inventions.

Because he's lonely and them porn tentacles are useless on their own.

There's an old proverb that goes "Just as metal sharpens metal, being around wise men makes one wise." I doubt that Krang ever doubted his own intelligence, but being around other theories and inventions that weren't his own, might have influenced him to some extent.

Or if you want the TL;DR answer to the paragraph above, then here it is - Cartoons don't always make sense.