You're downplaying the negatives way too much.
1. It definitely is a risk to level 1 rosh. Doing rosh this early means the roshing team will pick sub-optimal skills, end up clumped up in the rosh pit, and simply cannot engage comfortably into the enemy. Yes you can put up a ward, but the contesting side could just as easily use a smoke.
2. Most teams designed to rosh early are depending on taking the rosh. Sub-optimal spells, items, and hero composition means they desperately NEED the extra level and gold to regain an advantage. You lose rosh, you're walking into your lanes a lot weaker than you typically would be. Take a look at your own rosh team: DK has to waste at least 1 salve tanking rosh, SF will have -armor aura, Venge will have -armor spell, Jugg will have healing ward. Extremely weak at level 1 and your opponent could simply go tri vs tri and have the upper hand. You say spending regen isn't a major issue, but if you're now contesting their trilane, that regen is invaluable.
3. "Not checking rosh pit" is not a valid complaint. If you don't read the incoming early roshan or you choose to 5-man the jungle to place wards instead of checking it, that's on you and your team.
