Don't worry. Personally I don't mind harsh criticism because learning from mistakes is important. Developers can't be swayed by every single negative impression of play testers or players, but need to adjust their vision of the game (or future games) with the feedback gained from players. Some points may be there on purpose - like having a few puzzles that are not solved at a glance - while others are not like bad telegraphing of what the player is supposed to do, pixel hunting or unbelievable reactions of characters.
Jam games are inherently more flawed than "complete" releases, so I understand why people don't like to criticize too much and that's okay, too.