I wouldn't worry about it too much, Dota isn't nowhere nearly as volatile as SC2, doubly so when played on LAN with no ping advantage.
I don't think that's entirely true, it's not as volatile as SC2 sure but there are some ways to force a gamble and put even good teams into a bad position. Mostly this is done with extreme push strats, which are akin to 6pool, 4gates and whatever else(I don't really follow SC2 so maybe this shit isn't as viable nowadays but there's still SCV rushes and what not). Pick 2-3 healers, 2-3pushers, lane for 6-8mins rushing arcanes and meka and then 5man. Now the strat can be obvious in the draft and can be countered to an extent(either by picking similar/superior 5man or picking strong sidelane pushers who can splitpush 2lanes while enemy is 5manning and have a couple of long range nukers to delay the pushes), but it is a very stressful situation to have to face this sort of setup that you are not used to play in a bo1 direct elimination match, even if the other team isn't as good individually.
Now if you try to pick a standard draft to beat a team that is way superior in a bo1, it's unlikely there will be an upset, even though it is possible. The better team can always pick accordingly to the possibility of an upset with turtling heroes and a hard carry to guarantee that if shit goes wrong early, they'll still be able to win late.
However the 5man all in push strat can be risky even for the best teams. It doesn't have a high win rate but if you don't handle it correctly you'll lose badly.
That's why I agree they should have tried to fit bo3 from round 2, but I guess they need that break between prelims and real games. I think the idea of removing the bottom 2 teams of each group could fix this by cutting one round entirely from the loser bracket. If you end last or second to last in your group after playing 14games, I think well, that's that, train harder and come back next year.
As for TI2 situation, 2 teams in the LB went past round 2, I looked it up before the tournament started since we had the same argument. Tongfu went up to round 3 before being defeated by DK who had dropped down in round 2, and EHOME went all the way to round 4 before being crushed by iG who had just lost to Na'Vi.