This is working as intended... ground damage will continue to damage someone even if they are unconscious as much as if that unconscious person was sitting on top of a blade barrier being impaled and turned into mince meat.
I remember being killed by Blade Barrier not too long ago, though I was able to remain in the bleedout state despite being ontop of it.
Can confirm, was present for this, and was able to toss a heal at them. I think there is a save that can get made, even while bleeding out in the barrier, because another member of that dungeon experience did bleed out, while laying on top of the on-going blade barrier. Though I didn't ask the player if that is what corpsed her.
As to the issue of evards...I would highly suggest playing a halfling
Getting done in by effects when it feels like there wasn't any counter-play certainly isn't a fun experience, but it's certainly a thing in the setting, and in 3e mechanics in general, I believe. An interesting interaction a friend had in a dungeon was having drown cast on them, putting them in bleed-out, and then having a monster cast phantasmal killer, corpsing him. There was some amount of rage, and laughter, about it at the time.
Best advice I can give in this situation is don't be in a situation where a mage is casting Evards at you. Consider if you opted into pvp stuff. And learn which monsters IC can cast Evards, and do so, so you can plan for them with things likes, stoneskin, or maybe ghostly visage.