Well, I haven't used the 620, but my anecdotal experience has been the opposite.

List of recent devices I own that are unbroken:

lumia 521, 950, and Kyocera Rise.

broken:

nexus 7 (screen after 2 months), asus fonepad note 6 (screen after ~1 year), galaxy s4 (won't connect to tower, probably my fault for installing roms incorrectly)

In particular the 950 has been dropped in the river in breckenridge, and the 521 in a natural hotspring / taken on many rainy hikes / dropped more times than I can count.

My 820 took one hell of a beating over the time between purchase and replacement. Its replacement seems pretty hardy too. Though I get the impression the build quality and sturdiness were far more variable between models than found around the 3110/3210/3310 era.