Eric Migicovsky, the founder of Pebble, on why Pebble failed:

The underlying problem was that we shifted from making something we knew people wanted, to making an ill-defined product that we hoped people wanted.

The whole read is worth your time, but Pebble gets tons of credit from me for validating that the smart watch was something real and people would love it, and it's a shame they never quite recaptured that magic they had in the early years.