Phoen1x

Since you are looking for pro and cons there really isn't a valid list that fits everyone. What one person finds good other would find pointless.
 
Any case the main reason to keep dual-citizenship.
1. Enjoy the benefits of being a citizen of both countries.  (obviously Pakistan has less benefits to offer its citizens but it still has them)
2. Laws for foreign nationals apply. You have to report your stay in Pakistan to the police etc, many are not enforced anyways but who knows countries can become progressive.
3. You lose NICOP as soon as you relinquish your Pakistani citizenship. So that free entry into Pakistan is gone. You would have go apply for a POC card(Also visa free entry for foreign nationals)
4. Certain bank accounts/tax/business accounts are not allowed for foreign nationals. 
5. Many government funded schemes are not allowed for foreign nationals. For example, you would not be allowed to partake in the Hajj Scheme that is funded partly by the Pakistan government yearly.
 
and Cons (not many)
1. Renewal Fees on multiple IDs for both countries.
2. That's about it. The US passport states your country of birth so if you think you can hide your background just because you have a US passport think again.
 
Oh last thing
NICOP renewal requires you to enter details for US passport that would automatically make you dual-citizen. 

In that place you write "Never Employed"

Well many have commented on the fact that she might not pass the medical or you will come into some other type of problems in the future, but from my understanding of your post you just want to apply for her right now and worry about those situations as they arise. Since your priority date will take 8-10 years from being current you are probably taking the right approach.
That being said, you already have an immigration attorney who will have more information regarding your specific case then anyone on these forums. I suggest follow what the lawyer has to say unless you have doubts in his competence then you should find another lawyer. Your case is unique and not many will know or have gone through a similar experience.

He would still have to count the spouse as the household size. But the adult children need not to be counted.