And what does the spell Contact Other Planes do? Reveal activation words and such?

You can still request gear from goodie mobs and kill everything else. Archons treat you tons better, the difference is huge.

Contact other planes just tells you IF an object has 'other properties' and what they are, but doesn't reveal any specifics. So it might say 'This item has special properties when used in combat' but it won't tell you 'invoke tel'arnin' to use dispel light in combat with this object.

There are lots of good mobs you want to killi instead of request from. Plus requesting stuff constantly is annoying. It's also bad RP to constantly request things you don't need, and also to be mowing neutrals down by the dozens for no reason. A neutral conjie gets quite sufficient mileage out of archons for mob fighting purposes (since you can usually just flee).

Honestly there are a lot of exPlore situations where demon or devil are vastly superior to an archon (especially if you are with a good melee buddy)

It's hard to beat an acolyte with an archon. I mean you can altruism your elemental which goes a long way to overcome the small group of mobs conjures have s rough time with

Especially Acolyte. As an Acolyte you'll waste all your time defending, retrieving or helping raids, plus running all over to do this and that. Either you do a really bad job RPing, or you give up a ton of explore time that I'm pretty sure cannot be made up by altruism's admittedly significant benefit.

The same applies to all other cabals but Herald, to different degrees, but I don't think there's any one that gives you a mechanical advantage that outweighs the obligation to participate in cabal stuff. It gives you allies, but if you're planning to explore with allies, be a healer, bard, trannie or maybe invoker.