Not if you are using spanish. As a native Spanish speaker I say it is generally acceptable to use them, even instead of points and it's encouraged in some style-courses I've taken.
As for me, I prefer to use points. Not only it saves me the trouble of switching styles with the languages, It also helps me be clearer as a writer. It's a real hassel to read spanish for that same reason. After using English for many years and german to some extend, I find that using points is so much understandable to read.
The object does not depend on the position in the sentence, but rather on the meaning it has in the sentence/clause. Here kion is the direct object of vidas; it indicates that it is not the thing doing the seeing, but rather the thing that is being seen. If you swap the clauses around, the essential meaning of the sentence remains the same, i.e., kion is still the object of vidas.
The sentence Kio mi vidas, estas tion is grammatically unsound (both because Kio mi vidas is wrong, but also because estas tion is not correct either, as esti is a copula, i.e., a ‘connecting verb’.)
Hope this helps!