Sanook,
As you say, very few 4-engine a/c about. Several Virgin Atlantic 747 and their sole A340 (at LGW), the Phuket and Air Atlanta 747s. On 3 engines, North West and DASAir DC10, VERY occasional Portugese L1011 and of course our resident C130 Herky-bird (Air Contractor), 4-eng turbo-prop.
All the rest are twins, and no reason why not!
Cheers,
TheOddOne