Are "card consolidators" like Apple Pay, Coin, etc. useful? I would say it depends on, it really depends on where you shop and if you are ok still bringing a backup card. I have been using both Apple Pay and Coin for the last few months interchangeably when I can. I know the field is still young and has a long way to go however the support really makes it tough to justify. As well as when I first ordered my coin almost 2 years ago I had probably more like 5-8 cards possible in my wallet now I have 2 payment cards on average.
So far I think that the goal of consolidating your cards into one device seems like it is definitely attainable eventually. However, I don't believe any of the available options has made it there yet. For me to consider them there they will need to be in the neighborhood of 98% plus payment processor adoption. So both when you try to add a card and you try to pay you do not have to switch to another card.
I love it when technology makes things easier and this would definitely be an area I'd like to see improvement in. However, rightfully so the payment processors are slow to adopt these new technologies. I personally build software for a living and honestly the hardest thing I've ever encountered is working with payments since there is so much that can go wrong. The payment can fail, succeed, half authorize, considered fraud, etc. Which there is a plenty of edge cases as well as laws you will need to deal with.
Which brings me to my final point security. I do feel like Coin adds less security than Apple Pay does. Coin primarily adds security in the case you forget or lose the card. It will remind you if you leave it behind and will also lock if you are not around. With apple pay it handles all of that a little different you still get the loss security that is built into the devices. However, it does not actually use your credit card number but a reference to your card. So each payment is unique and makes it unusable even if someone has the information. Which almost makes me feel safer than the chip cards in the security realm.
I think if you are interested in tech or specifically the "Internet of Things" they are both definitely worth a look. Even if they are still in a young stage they are ready for everyday use. Just make sure you bring a backup card just in case. As well as the only way they will get better is by failing and iterating. Just like anything good these things will take time but it will be worth it.