I've reread the OP and now clearly see the single word (!) which distorts the holy meaning of the whole thing and irritates the most of the commenters. I must immediately update it.
The OP title shall be now read as:
Why doesn't Stack Exchange reward some reputation points for installing
& using mobile app?
I agree that rewarding reputation for solely using mobile app makes no sense as it doesn't generate any research effort for the Community. If I were you, I would also downvote this concept.
Another point - is installing SE mobile app, which definitely worth a reward to those who installed it. They might be one time rewarded with +5 rep.
A few examples of the concept:
- establish a new Dropbox account and get 2Gb as a reward.
- register Lufthansa/Emirates/Delta, etc. Frequent Flyer account and get 500-1000 miles start reward.
- establish an Assembla account and get a free repo up to 1Gb.
The true meaning of a reward is to stimulate users to use the services. Either ways. What currency does SE use to stimulate interest and activity? You know the answer.
Original title and body
Why doesn't Stack Exchange reward some reputation points for installing & using mobile app?
Imho, installing and using Stack-Exchange mobile app shows trust, interest and loyalty. Which is way more serious than just upvoting a silly comment.
This action shall be rewarded :)