The 2 problems
You are correct that if there is something lacking, then there is no perfection in God, so God is perfect. It's also a well established teaching that creation is NOT to complete Him.
First problem: Does it mean God doesn't desire us? How can a God who doesn't desire us be said to love us? Can we understand such a love?
Second problem: Add to this, God's "desire" to be glorified, implied by the answer to Q.1. ("What is the chief end of man?") of the Westminster Shorter Catechism which says "Man's chief end is to glorify God, and to enjoy him forever.", which can dangerously be misunderstood to imply that God is a vain deity who demands praise from His creatures.
The Biblical "data"
The standard mainstream answer, based on God's revelation of Himself in the Bible, that is processed into the classical doctrine of Divine Simplicity, is that God possesses the standard Christian divine attributes which include BOTH those implying perfection such as
- Aseity ("God is so independent that he does not need us", Acts 17:25)
- Immutable ("God cannot change", James 1:17)
- Impassibility ("God cannot suffer" although God does suffer in his human nature, i.e. Jesus on the cross)
AND ALSO other attributes implying emotion:
- Graciousness (Ex 34:5-6: God declaring himself to be "compassionate, gracious, slow to anger, abounding in love and faithfulness")
- Goodness ("God is the final standard of good, and all that God is and does is worthy of approval", which encompasses his kindness, love, grace, mercy and longsuffering (cf Louis Berkhof)
- Love ("God is love", cf 1 John 4:16b, even the "fountain" of love since "We love because He first loved us", cf 1 John 4:19)
The 1st problem sharpened and answered
How can we understand logically that God is perfect YET having emotion (including love, compassion, etc.)? Trinitarian understanding of God conceives the Holy Spirit as the love that spirated between God the Father and God the Son, so in his immanent life God is Love himself. This love then FLOWS OVER into creation (part of God's mission, God's work, God's economy, etc.) which we can conceive as an "art" suffused with God's attributes of perfection, goodness, beauty, etc. which humans (possessing the image of God) can perceive in terms of those qualities, instead of perceiving creation as mere material atoms and energies.
Thus God's transcendence is preserved (creation is external to God) YET we can also say God is immanent in creation because God can be said to be 1) "present" as a particular thing's "ground of existence" (even in mountains, not just trees and animals and human beings) as well as 2) present in rational souls as the Being who has a one-on-one personal relationship with, in love.
True love desires the perfection and the happiness of the beloved as an outgrowth of our love for our own perfection and happiness (thus the greatest commandment: love your neighbor as yourself). True love is a GIFT to which the lover doesn't need recompense. Most human beings cannot love 100% disinterestedly (not is it required) but God can since God does not need us. His love is pure gift.
To His creation which we can like as God's "art", we can understand God's desire and love for us like an artist (say, Mozart) who creates a musical composition (such as The Magic Flute) that can be forgotten / appreciated without reducing/adding anything essential in Mozart's own person or perfection. But God / Mozart desires the recipient (us) to enjoy his musical creation and will be happier to see us becoming a better human being as a result. No analogies is perfect, but I think this best illustrates how God can create WITH desiring the creation's happiness but WITHOUT reducing His perfection.
The 2nd problem sharpened and answered
Recognizing creation as the OUTFLOWING of God's love, human beings naturally want to give thanks and to praise God out of the sheer recognition of the creation's beauty and its origin. God's "desire" to be glorified can then be correctly understood as a prescription for OUR benefit: that the proper functioning of our soul should include the worship of God as our natural response. To not worship and glorify our creator is a defect because it is unnatural not to give thanks to the agent of our existence (thus, it is natural to give thanks to our parents as a secondary agent of our existence). Since God desires our perfection (1st problem), God also desires our worship in this sense, i.e. for our salvation and for our ultimate pleasure as creatures.
I still want to find a good resource that substantiate the above answer, which I will edit into this answer later. But I hope this answer is merely a clarification of a well established doctrine.