I rarely feel that I have much of substance to add to the Drupal community when it comes to the front end, but having seen field collections abused in 3 different clients over the last few years I am compelled to write about how not to use them. It boggles my mind that I've seen the same problem crop up so many times, and I expect that this has to do with so many new front end developers for Drupal out there in a needy market - so needy, in fact, that those who shouldn't do front end work yet are being highly paid for mistakes that should never be seen outside of a learner's sandbox.
It also speaks to the value of some technical leads out there, but with turnover rates as they are in the Drupal community, projects suffer.
The beauty of field collections is the ability to treat multiple fields as a single field within the front end. This is handy in certain use cases, such as when showing dynamic information on a specific item. The classic example of how they are useful is for a playlist. They might be useful for a library of information, a collection of quotations and any number of other bits of dynamic data. In essence, the front end gets to do some of the heavy lifting which was once reserved for the back end and custom modules. It is awesome.
It is not, however, something you use to display static content - particularly through nesting. I'm sure someone can come up with a use case for when it could display static content effectively - in fact, it seems that a few have - but the use cases I've seen do not qualify.
Now, by all means, keep doing it - it seems to get me paid to fix your work.
Just because you have a hammer doesn't mean everything is a nail. KISS. Assorted other cliches.