Intel only has a very bad reputation.
Intel GMA 950 was crap.
3100 was bad, 4500 was still abysmal.
Intel HD Graphics (Arrendale) was a huge jump in performance and the first useable one for driving everything in 2D. Still not great in 3D.
Intel HD 3000 was another huge jump. Now you could play almost all 3D in low settings. The GPU was especially good in low settings even compared to Nvidia and AMD. Intel optimzed for that because they never intended to put a GPU in that could handle high settings anyway.
Intel HD 4000 was another big jump and finally destroyed all the low end GPUs.
The thing is Intel is still judged by those old GMA crap but they put a huge effort into the HD series. If you compare the speed increase to AMD, Nvidia they almost are equal now.
They also have the edge in process technology. They use 22nm already.
Stuff that AMD or Nvidia can cram into such a small space next to the CPU wouldn't be any better.
Compare the AMD Fusion onboard GPUs for what AMD is capable. They use more space for a more decoupled GPU and only win on the best incarnation.
With or without a lawsuit Nvidia couldn't compete anymore power efficiency wise with some separate chip that includes the MCH, or just barely. You wouldn't see any significantly better performance.
The 9400M from Nvidia was the first really decent integrated GPU and it was hailed by Users that don't do anything more today on OSX. It got smoked by the HD 3000 that still many complained about.
The 320M was the first integrated GPU that could beat some available dedicated GPUs and it is only just as fast as the HD 3000. Everybody was proud of the the 320M because it is oh so great.
HD 4000 is faster and a 620M would consume more power than it is worth.
Especially in the Intel ULV chips it is not worth to use anything else anymore. That would be a 15W CPU + 12-18W GPU. Integrated GPU just rules here.
If you need more get serious and go for a 650M that really makes a huge difference.
People complain because they don't look at the facts only repeat the reputation they get from forums which needs some years to change.
In fact the video acceleration stuff in the Intel GPUs was more than just on par with AMD, Nvidia for extremely low powerconsumption. Just going over the PCIe bus would have wasted more.