To be honest, Zenos being a sympathetic wouldn't make him different from what already exists. We have had very few antagonists who at the very least don't have a solid justification for their actions, even if they are misguided. Having a villain who is just a cruel and evil personality is actually somewhat different.

I would say two things about this.

1. Having an really evil character as a villain can be fun. More over there is nothing saying he will be our only enemy. We had several antagonists we had to contend with in HW. I suspect we will have a number of players we are caught between again.

2. Zenos being a villain, or even Varis being a villain, doesn't mean we won't have sympathetic Garleans. More over Garleans who aren't neccesarily loyal to either of those doesn't mean they won't feel loyal to Garlemald itself. Being loyal to Garlemald doesn't necessarily mean the same thing as loyalty to its current ruler.