cbwjm
Seb-wejem
It made sense from a point of view where non combat encounters were effectively not factored into your resource usage for the day... but to my mind that was a bit problematic in itself, especially since it wasn't done particularly consistently.
I do wonder what the criteria used to decide this was. I mean obviously there are some spells that shouldn't be rituals (spells that cure wounds or deal damage), but why not magic circle? Thematically it's a perfect fit, and mechanically there's nothing wrong with it, especially when something as busted to have on tap as leomund's tiny hut is already a ritual...
Anyway, I like the ritual system, but I dislike the current spell lists. They've just been meaninglessly changed in a myriad of ways from previous editions, and it just causes a heap of problems.
I feel the same about the ritual choices as you do. I could probably make a fairly decent list of spells which I think should be rituals but currently are not. Some spells essentially already are rituals (albeit with casting times of 1 minute to an hour instead of the 10 minutes of a ritual spell) but require a spell slot, probably so that people couldn't just perform a ritual to conjure an elemental for no resource cost, allowing these spells to be rituals would lead to a very different kind of game, I think, possibly with many people summoning up elementals to help in their battles.
Spells which I think could be rituals without any major change to the game are various protection spells (protection from energy, protection from evil & good, & magic circle [as you say, it's a perfect fit]); spells like Dream (already a 1 minute cast time), Glyph of Warding (an hour cast time), guardian of faith, guards and wards (10 minute cast time), and scrying (also 10 minutes to cast). Secret Chest seems like a good candidate for a ritual as well.
This isn't a complete list and I may not have thought of all of the ramifications of making them rituals, however, I think that WotC could have definitely been more liberal with their application of the ritual tag.