Choosing to use them because your customers like them is exactly why it's a bad idea. Customers would like $1 lattes and free foot massage too, but I don't think you'll be doing that. If that's the only way you feel you can get people in the door, you need to re-evaluate what you're doing. Either you lack confidence and shouldn't, or your product needs improvement.
This sort of thing goes along the same lines customers requesting you to add soup, a lunch menu, more flavors, Vegan pastries, Vegan gelato, whole grain breads, etc. ALL of which I say "no" to.
The use of discounts as a mechanism to drive customers into your door, (other than at Grand Opening, and possibly with the introduction of a new product), will not produce a good foundation for a long term customer base. If you get 500 customers coming because of the coffee coins, the majority will leave when you cut them and anything like them. If you get 500 customers coming because of your product, unless they move, you'll probably have about 500 customers.
I have good things to do with my time, but if I take the time to answer a question, be certain I'm not merely posting my opinion. People wiser than me are saying the same thing, and have been for years. I like to see businesses succeed, get on the right path. I'm selfish, if there's a chance you can be great, I'd like more places to go. There a shortage of spots worth visiting, and for those that are starting, it'd be great to see you around long term, focusing on your product rather than the gimmick.
The fact that you asked the question shows you know your focus should be elsewhere, but you're just not sure how. And, as many new owners you are worried about slow beginnings and get caught up with the "numbers through the door" this sort of thing brings. Beware of the long term consequences, that's all I'm saying.
From time to time you can give a customer the gift of one "on the house"-- those who deserve it. Otherwise, reward your customers with what you do best. Why would they ever want more?
I wish you the best in your business.
