Hi! Welcome to RAF!!!
You should make an Intro thread!
I understand the pity for the Yeerk, but, at the same time, they chose to forcefully enslave races, murder, and commit all manner of evil wrongdoings. Now, if they had stayed with Gedds, then that's another story. They were darn near symbiotic(Think I'm spelling that right), but, instead they chose to steal Andalite technology, and force themself upon the universe in many, many evil ways. Now, that's not to say that all Yeerks are evil, just look at the Yeerk Peace Movement. I believe that a lot more of them would have been peaceful, had the opportunity presented itself.
However, I also believe that had they never done what they did in the first place, the Andalite stealing, and waging war, yada yada, then it would have been very, very possible to find a way to get them hosts, in a good way. Probably some advanced form of cyborg/android. Something near flesh, but still not.. Y'know, horrible. And, of course, the Andalite Morphing technology could have become very useful to them in due time, and they wouldn't have had Seerows Kindness as a law had the Yeeks never screwed that up..
So... In short, I do pity the Yeerk for the reasons you gave, but I also think of them a bit like Nazi soldiers, just following orders, trying to make their own life better, but hurting others in the process. Thus, very little sympathy, a lot of pity, though.