Have you ever said "simplistic" when you meant "simple"? Here's an explanation of the difference between these two similar words.
Vicki K. from South Dakota notes that she often hears designers on HGTV say "simplistic" instead of "simple," as in "The modern room was designed to be sleek and simplistic." She asks, "That's not right, is it?"
No, it's not right. At least, it's not right if they are trying to say something good about the design.
Simplistic means that something is oversimplified or lacking something important. For example, if I were to say that affect is a verb and effect is a noun, and I didn't talk about the exceptions, that would be a simplistic explanation. I left out important details—the exceptions.
To say the room was designed to be sleek and simple means their room is clean, unadorned, or not overdone. That's clearly what the designers mean when they're talking about their work.
In this context, simple is the word you want, not simplistic.