Szczepan, do you mean that it isn't important if people are leaving openings where they can be hit? I understand why hitting people wouldn't be an indicator of martial effectiveness, and also that people sometimes use hitting to cover up errors, but I would have thought that if you and your partner are in a position where they can hit you, that's basically bad? Shouldn't you be trying to get behind them, and to get them off balance, etc?
This aspect is simple and complicated at the same time.
Of course the consciousness of the existence of the openings is important, we can use them to hit or counter the attack or the technique. But resuming OP criteria for aikido practice to "we are pretty serious about atemi use" means he is living in some kind of fantasy.
In aikido practice we have predefined uke and nage behavior (even Tomiki fighters can use only predefined attack and 16 predefined techniques). It means that nage knows what attack arrive BEFORE it happens physically. This already is an opening from attacker side. Using this opening to hit or counter is a very easy task, and has nothing to do with martial aspect of the practice. Under such conditions, even a novice is able to hit many times an experienced attacker; it is not a big deal. So ‘being serious about atemi' is IMO not valid criteria to evaluate another dojo.
The examples of the valid criteria: posture, precision in technique execution, position of the nage in comparison to attacker, the correct use of the angles for entering into attacker and when you unbalance him, the correct use of your own body, timing, intent etc…
If somebody is not aware about these criteria, it can be developed correctly by practice of the weapons.