I wouldn't use the phrase "unnecessary to use a heatsink". The thermal design can't be ignored.
A bit more info on the LEDs(mid power) and the heat sinking material.
http://illuminationinfocus.com/news/4/12/8
from the article said:
the new Philips design uses some type of thermally conductive material to draw heat toward the flat center of the lamps where it can be dissipated into the air.
The bulb is rated 60W equivalent 10.5W exactly the same as their current non dimmible 10.5W bulb. The amount of heat generated and have to be dissipated is the same.
In the current bulb the LEDs are in a cluster in the middle of the top of the heatsink. The heat from the LEDs in the center have a hard time getting out because the heatsink is already heated by the LEDs on the outside.
With the new bulb the LEDs are all the same distance from the (rather tiny) heatsink in the middle. This makes for better heat management. If the tube is glass or other fairly good thermal conductive material, then the surface area of the heatsink (tube plus the flat area in the middle) is quite large. The loop is much bigger than the A-19 incandescent.
Philips may have decided to just accept a short life from the LEDs in order to meet the price point.
Philips rated this bulb at 25,000 hours. In the last couple of years they have rated most of their LED bulbs at 25,000 hours.
In the olden days both Lumuleds and Cree rated their LEDs at 50,000 hours
at 25°C. Then both start rating their LEDs at 85°C.
The companies that still use 50,000 hours follow the time honoured tradition of companies stating SSC-P7 flashlights are 900 lumens. They just print the biggest number they find on the LED manufacturer's website.
Another interpretation would be to say that Philips just assumes that the consumer will stick the bulb in an enclosed fixure, and the bulb will suffer early lumen loss regardless. Why bother implementing a good thermal design if the consumer just covers the bulb in insulation?
Packaging usually say "Not for enclosed fixtures". Except for a few companies like Xledia and Switch. We'll have to see what Philips prints on the package of this bulb.
Somewhere else on the packages Philips also mentioned 3 hours per day. I have 2 Philips bulbs fail on me in 6 months. A MR16 in computer keyboard light and a nitelite. Both run more than 3 hours per day.