But why dont they step into 5V line
1) at 3.3V you get 4 times more chips than at 5V
2) the big markets want less power consumption
3) if they can sell a million chips to acme microelectronics, they (or anyone else) do not give a hoot about selling 100 to Sanjeev.

I love 5V because of the better noise immunity - no other reason, but to achieve certain things I have put 3.3 parts on some of my boards. One 'warning' use 3.3 volt parts to directly drive 5V parts and your noise immunity is shot, you need to use a chip such as the LVC4245.

Erik