Completely serious.
I can go make a list of players who are perceived as more solid, and reliable, and proven players than Omri who make less than $3 million. Hell, Matt Barnes has seldom gotten much more than $3 million a year, and he's proven his productivity and reliability with tons of playoff teams and started most of the last 6 years.
Does that make either of us right?
We'll see.
We can argue all day about Omri's "real value" but roster decisions don't work in a vacuum.
Omri has already played here and have a cerain chemistry with other team members, he is still 26 (unlike some guys you mentioned), he wants to be here, he seems to get along well with Karl's coaching and most importantly he is already on the team- now that is important for two reasons- the first one is stability and the second one is cap space.
If you let Omri go than you'll need to find a back-up SF, now if you want a back-up that will cost more than minimum salary you will have to surrender cap space, and instead of investing where you need to you will invest it on a SF which I doubt will give you better production than the one you already had.
Now of course I'm not advocating you to overpay him into a bad contract, but I will be willing to pay a little more for a guy I already have and renewing him won't take cap space.