Why? Why does he hate them?
If you fail to dodge them, you're basically dead meat. Getting caught in goo isn't just a
malus to your combat skills, it more or less takes you out of the fight entirely, to the point where a single attack aimed at you would be enough to kill you. The only way to avoid that is to dodge the goo bomb entirely: it's basically a save-or-die seal.
Which could be alright in and of itself, failing to dodge an explosion is hardly good for your health too, but the TN Goo Bombs use scale with the Sealing level of the sealmaster who researches them. So it's not just a TN 40 save-or-die seal, it could be TN 50, 60, 70, or more. And it can't be retconned away because we already made explicit use of that in the Chuunin Exams by having Jiraiya's goo bombs on-hand to crush our opposition with Jiraiya-made TNs.
(This also, notably, raises the question of "why didn't Jiraiya scribe a few hundred of these so that every genin in Leaf could roll at Jiraiya TNs if they so chose?", a simulationist tangle with no easy answer.)
The most the QMs have been able to do to curb this is to add a cap to Goo Bombs, I think around TN 60, so that you
can get to pretty high numbers if you're borrowing from a high-tier sealmaster (like we did, in the exams, which forced the mechanics to stay that way) but it doesn't just scale up indefinitely.
Anyways, let's make a goo bomb rune! Maybe those'll roll
twice Hazou's effective PS!