DryRun:
it is relatively harder to find compared to the UNOs and Nanos
It's a very new board. I'd guess that if it's adopted successfully by the Arduino community the availability will get better. Of course you may argue how can it be adopted by the community if they can't get it?
DryRun:
it is VERY expensive compared to the other Arduinos
You said yourself it has a lot more features compared to the Uno and Nano. The parts cost for an Uno WiFi Rev2 is much higher than those boards.
DryRun:
and together with all the clones out there.
The clones will always be cheaper than the official Arduino boards. All the clone manufacturers need to do is send the design files off. They didn't need to pay skilled electrical engineers to design the hardware from scratch. They didn't need to pay skilled software engineers to provide a high level of support for the products. They didn't need to pay skilled technical writers to produce documentation. They didn't need to pay Italian manufacturers to make the boards in compliance with strict environmental standards. The didn't need to charge shipping costs which are far higher than the subsidized rates from China. When you buy an official board, you are supporting Arduino's ability to do work that helps all members of this community, regardless of where they bought their board. When you buy a clone, that money just goes to keeping the clone manufacturer in business. Very few of the clone manufacturers contribute in any way to the Arduino project.
DryRun:
Is the design for the wifi rev2 closed-source?
Not at all. The design files are available for download right there on the Documentation tab of the product page:
The licensing is CC BY-SA. Feel free to make one and sell it for a lower price if you like.
DryRun:
3. Why don't you pack a Bluetooth LE module into it to further increase its relevancy with current wireless trends?
The u-blox NINA W102 module used to provide WiFi communication also does BLE: