1/8" NPT parts are cheaper, and less bulky, but are still strong enough to do the job, which is generally why we use them. 1/8" NPT is actually about .4" diameter, while 1/4 is .54", in case picturing the sizes was throwing you off.
The solenoids we use usually have 1/8 or smaller ports, while the needle valves may have 1/4 or smaller ports, and we may use an adapter for both, either, or neither.
By the way, one other solution for the odd angle (possibly the most common pet peeve about the VTS series) is to go straight out of the port for a couple inches, then use a 90 deg elbow forward, and then another 90 elbow up. The first elbow will allow you to level everything to cardinal directions.