If you hiked in sandals for an entire year, perhaps you avoided (or failed to avoid) varied conditions.

On a number of trips one might spend a day walking in sandals, a couple of days in mountaineering boots, and then back to the sandals for some or all of the walk out.

It may be best to have several types of footwear for various sorts of trips, while scrupulously avoiding dogmatic views of what one supposedly MUST or must NEVER wear.

I generally bring along sandals, and may or may not hike much in them and or bring other footwear.

One of their great and obvious advantages is in fording streams -- and even (for me recently) in using streams as trails.