That wild leg is considered a potential safety hazard because folks adding new (110v) circuits to a panel that is fed in that way MUST pay close attention to which breaker slots in the panel are fed by it. Every 3rd slot is the wild leg.

For new construction or service upgrades most local codes will demand you to have two breaker panels: 1 main one for incoming main breaker followed by high line (208-240v) 2-pole or 3-pole breakers in it for single or 3-phase loads, and a 2nd single-phase panel fed from a large breaker in the main panel. The 2nd panel is only fed by L1, L2 and Neutral. This 2nd panel is for all 110/208V lighting and wall outlet power, breakers in it will be either 1-pole or 2-pole to respectively deliver either 110v from L1 or L2 referenced to Neutral or single phase 208-240v from across L1-L2. The driving point is that new circuits can be added at will with no regard to that wild leg.

The most common wye service connection from the utility's transformer eliminates any potential for incorrect wiring. Leg to leg will always be 208-240v and any leg to Neutral will always be 110-120v.

As for actual voltage supplied, that is a bit of a sticky issue... Most utilities want to give you 3-phase 208VAC (usually more like around 213V) vs 230-240 because referenced to Neutral you will get 110VAC. Them supplying 230-240VAC splits down to around 115V up to just over 120V.

Is the higher voltages better? Yes. As you said there is lower current pulled so less stress on the front side of PSU's. Plus, it gives you greater margin to keep running if there is a brown out where the line voltage drops though in the US the brown out margin rarely matters.