Why are some parked aircraft angled away from the taxiway center line?
If the pavement is wide enough and strong enough (both of which will vary depending on the model of plane) for staggered parking, then that is the most space-efficient option.

If not, then you have to park them single-file. Simple geometry tells us that turning planes roughly 45 degrees (◼️◼️◼️) will be more space-efficient than nose to tail (). For the same reason, some very congested airports have tighter angled parking at gates, whereas those with plenty of room use faster straight-in parking.