Until your LED bulb starts making a strange noise and you discover these things actually have a cooling fan inside of them. This thing WILL fail if kept running for a long time.
I believe switching capacitors in the power supply are what limit the lifetime of most LED bulbs - electrolytic caps being one of the worst offenders. Good thermal management helps mitigate these problems, but a lot of failures are chemical in nature - caused by the degradation of the capacitor's electrolyte. This is why we've all seen the capacitor choice in motherboards and PSUs used as a marketing item.
Full disclosure: I used to work for a well-known LED lighting company, but please take the above with a grain of salt as I am not an electrical engineer. [Edit: And of course, these views I've expressed are my own and not representative of my past employer.]