Yes

To be fair, the Hansen's were irresponsible about how they handled a lot of things concerning their quest to study the Borg, greatest among which simply not respecting them enough as the very real threat they were, letting themselves get overconfident with what successes they had and pushing their risks further and further until finally their luck ran out.

So bringing the would-be Seven along with is really just the tip of their irresponsibility...but also probably the one that had to suffer the consequences of their choices the most.

Not really. They wanted her with them. That is being responsible. Studying the Borg may not have been the smartest option to begin with, though.

Absolutely. There was no need for them to bring Seven, who was a young child, with them on a dangerous mission like that.

Why? The same reason a exploratory/science vessel like Enterprise-D should never have civilians on board. There's too much danger in space. Sure, it's rare to be in danger from ships or spacial anomalies like a roaming black hole or comet, but the danger is there. It's one thing if your husband is in the science division while their wife is chief engineer.

YUP! Well they were dumb in general.