I think accepting Bitcoin is a good way to promote both Bitcoin and your store because
- You can attract customers who are interested in using cryptocurrency for purchases.
- You can also attract customers who wanted to venture a different method of payment.
- It is also possible for your business to open globally or access international customers because Bitcoin is a p2p payment system that knows no boundaries.
- It is also a good way to raise awareness about Bitcoin people will possibley become interested on Bitcoin whenever they see the banner of your store stating that it is accepting Bitcoin
from the several points you mentioned, increasing awareness of the use of bitcoin is the main purpose why adoption is done. Ordinary people who don't understand bitcoin don't know how useful bitcoin is for payment and is an option for payment today. not only as a means of payment, but also can be used as a good investment tool if you can manage it properly.
The stores that start accepting bitcoins depend on the regulations of their respective countries. Most of those who have adopted bitcoin are from countries that fully accept bitcoin. But some developing countries only allow bitcoin and other cryptocurrencies only as commodity tools and may not go beyond that.