Yeah, that would be nice, but I think they are trying to balance out Ritual casting by making some spells last for longer/as long as you maintain concentration. So if in 5e you would probably re-cast Shield of Faith in between encounters, you don't need to do that BG3 if you maintained concentration (which admittedly can be hard to do with the Burning status ticking away). Hence you have more free spell slots to cast spells in general.
In 5E you can't cast any spell as ritual. Only the ones tagged with "ritual" and "Shield of Faith" isn't one of them
But mostly stuff like "detect magic" or "identify" for example.
The list of ritual spells also isn't really that big, bust most of them are some really nice quality of life spells.
http://dnd5e.wikidot.com/spells:ritual
