Clones don't fare well in Roddenberry's universe, technology unchained is fine, but improving human beings...well that just dangerous!
The largest sample of clones in ST are the Jem Hadar and Vorta, both of whom do not share admirable traits, and are at the mercy of their flaws...the Jem Hadar must be on white, and Vorta are basically whimpering, servile drones to the only non-clones in the triad of the Dominion.
Which has nothing to do with the fact that they're clones, but only with the fact that the people who engineered them are tyrants. What you said was that Trek treats clones as "abominations," and that is completely wrong. If anything, the Jem'Hadar and Vorta were often portrayed as victims of the Founders, objects of sympathy rather than disgust. The idea that Star Trek
would treat any entire category of beings as an "abomination" -- in other words, would treat that category with hatred and bigotry -- is anathema to how Star Trek
The Riker example is not the only one from the Mariposans: they suffer bio-technological flaws, they are thought of as not being imaginative, and are stiff...only combining their DNA with a more viable non-clone people make them worthwhile to carry on as a civilization.
But that's because they'd been forced to rely exclusively
on cloning a very small gene pool for hundreds of years, and had fallen prey to the technical limitations of the process. (In fact, the episode's concept of "replicative fading" was rather prophetic -- there are similar problems with cloning in reality.) Saying there's a problem with cloning
is not the same as saying there's a problem with clones
, or that they're "abominations" that don't deserve to exist.
The Ibudan clones were the result of a murderer and criminal who only wanted to use the technology to survive.
But Odo overtly stated that killing one's own clone was still murder -- which means, by definition, that clones are considered people and are equal to other beings in the eyes of the law. Again, that is not consistent with treating clones as "abominations."
Ultimately genetic creations in ST are humanity playing "God", with the UFP forced to stay out of it by law, and this is pretty much in tune with Roddenberry's views.
Actually it's something of a contradiction to Roddenberry's views, since he generally painted technological progress as a positive, beneficial thing. "Don't play God" is the way most mass-media sci-fi treats technology, but Star Trek
has generally tended to be less cautionary and more optimistic about the power of technology. The main exception has been the franchise's resistance to transhumanism of one sort or another (AIs, cyborgs, genetic augments), but there are exceptions to that in characters like Data, the EMH, and Bashir. (TOS was a lot more prone to see AI as a negative than its sequel shows were; most androids and thinking computers in TOS were dangerous or evil, but in TNG etc. they were usually nobler and more sympathetic. Maybe the next generation of Trek shows will be more tolerant of transhumanism than the previous one.)
And again, while the process of cloning has often been shown in the wrong hands, that's a far cry from expressing hate toward the clones themselves.