Because a heatsink is unnecessary.
The motherboard acts as the heatsink for these modules (depending on the installation, e.g. a heatsink is required for the VRM in a GPU)
In a desktop though It's not needed.
They're fine, don't put anything on them. Did you randomly come up with that or is it there a reason?
They are fine because you cant OC with your laptop.
dont click! lost my p90 skin
Why do you go through all this to mod a laptop? Just use it as its intended.