What conditions a freestuff maker puts on his work is up to the freestuff maker. Whether some conditions are wise to put on the freestuff is a totally different matter. I could put a condition on a freestuff item that says you can only use this item on a PC with an AMD processor and not an Intel processor, or that you must stand on your head in a yoga position while using this item, or that you may only print renders of this item on recycled toilet paper. Ridiculous conditions, but I'm free to put them on the item. WIth the result that nobody will use it, and that nobody will find out what quality the item is.
So I prefer to allow both commercial and non-commercial renders, to allow redistribution in unmodified form, to allow modifications and redistribution of those modifications on the condition that I'm mentioned as a provider of base materials, and even inclusion of my freestuff in commercial packs, on the condition that the readme that goes with my freestuff is included with the pack - so the purchaser of the pack has exactly the same rights on my freestuff as if he/she had downloaded it from the freestuff section here. I believe these conditions make my freestuff more attractive to end users, and that more end users will find out what quality they can expect when they download something I made.
And that reputation is going to be a great help when I enter the marketplace.

P.S.: no need to worry, I won't stop making freestuff. It's way too much fun.

The pen is mightier than the sword. But if you literally want to have some impact, use a typewriter

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