Just a guess, fibre optics is relatively new to the Malaysian shores, so companies can only offer to push this service to densely populated areas like the Klang valley, Penang, and certain parts in KL.
TMNet is probably to lazy or lack the financial resources to upgrade their lines to fiber optic lines, so we are stuck with slow speeds and inconsistencies..
Now we should take a cue from Estonia..
http://thirdpipe.com/2009/04/24/esto...-next-100mbps/