First of all some information in the question needs enplaning before going any further.
- About devas aspiring to be humans
This is the full story...
Just like any other being the karma of devas run out.Then something amazing start to appear.The flowers they ware start to loose their beauty and die (Like our flowers in the evening),their body's start to sweat for the first time,They loose the appeal for the comforts in deva realm.
When others see this they come to these friends who are about to leave them and say this "Focus on the Human realm,you can continue your path there.You can even come back to us."
Then they follow as advised and come for a birth here.
The common misunderstanding
Do this before believing what i am about to say.
Go to "Youtube" and watch few executions by terrorists,If you watch anymore than half a dozen you will need some help to sleep today.
So what's the point of doing that?
This is why,
That was only few videos Devas are not bunch of playboys having a good time without a care in the world.As to "Suttas/Sutras" they are given territories
to look after,Some come down to earth to help the people in need (After all we are their children,parents,relatives),Some travel between realms to teach other the path to nirvana.
Unlike us they do not look away,You only experienced few tragedies and cruelty.They see it million times bigger all over the globe everyday.Not to mention the other realms with life.What is our pain they do see the pain in hell (the naraka / apaya).pain in those realms are nonparallel with any other,it is that high.
They are not covered from reality of life.
- One day a monk who genuinely tried his best to reach nirvana died
before reaching nirvana.Now he opens his eyes as if he just woke
up.He is terrorized by what he sees,"The deva realm." A lot of devas
were gathering to greet him knowing that he was a good monk.They were
beautiful and kind but our ex-monk deva saw them as if they were ugly
ghosts.With immense pain he came to see lord Buddha and told what
happened to him.Lord Buddha kindly advised him and asked him to
continue his practice.He went back to his realm and told his many
female devas (who were born for him) "I am continuing my practice and
i consider you all my sisters."
This is only one story,Let me present the details directly from lord Buddha..
Lord Buddha said that what happens there is more like what happens here.Just like in our world people who look away from pain and go get lost in joy exist there.The people who want an understanding search for truth,They get help from others and they even have discussion sessions with "Brahmas (Beings from the highest realms)".
If you think having anything on demand is going to harm concentration or the path to nirvana itself do this.
Look at yourself,now you are on the internet.Whatever you wish to have is on demand, you can entertain all of your six senses,go after any temptation for free!
Let me remind you...
Instead of reading about Buddhism you can do anything else right now.I mean what's wrong with us?, reading texts on some page about Buddhism!
This is the difference between common people and people like us.It's the fire that keeps burning leading us to try to find more meaning to life.This my friend is the spark that burns in any wise being in higher realms!
Also let me tell you some less known fact!
I hope you know about "Albert Einstein's - Relativity" because it will help you to understand this easily.
"Lord Buddha said beings in Deva realm have very long lives".The relativity comes in to action making us live in different speeds of time.
I know it was a bit hard to understand.Let me tell you a story mentioned in Buddhism that would do the trick.
One day a female in deva realm went to a garden with her husband and their friends.While spending time there she died because of her birth karma expiring.She was born among humans,she remembered her last life so she became a follower of lord Buddha and did many good things in hope of seeing her husband again.she lived a full human life and lied.She was born back at her place like she wanted.S she rushed to that garden of her last life they were still there and they asked an amazing question "Where were you in the morning we searched everywhere" she replied saying i was born among humans and lived a whole life time there.They were very sad and said "Oh how short is a human life!"
Get ready for the surprise of your life!
As to calculations given in Buddhism to deva Realms it has been only five days from Lord Buddhas leaving (death).There are still arahants there who offer doubtless advice to the ones who practice the path.
Looking at the Extra long life,A mind that is way faster and better than ours,Being in the company of arahants it is way better than being human!
Here in my country (Sri Lanka) where there is a Theravada practice we are often advised to focus on Deva realms because of the growing evilness of the world.Most of us plan to leave here,honestly i advice you the same if you do not reach nirvana in this life.The future world is not for us,it is for "kill or be killed" people.
About too much of good karma
There is no such thing,Lord Buddha said that any good karma is good no matter the size.
This is Lord Buddhas words.....
"There is only one friend to the beings who wander in sansara,it is nothing else but their own karma"
May triple gems bless you!
Please comment if you have any questions.