We see this so differently.
The fact that the spectacular doofus was a great benefit to his allies is what makes the Jar Jar character even
worse! Throughout the saga, people (and aliens) are dying while making a concerted effort to have even the most marginal/minor victory over the bad guys. That's an integral part of bringing a seriousness into Star Wars. Jar Jar did nothing but undermine that. His effectiveness at helping in the battle is a big part of the problem.
Tons of Rebels died throughout the SW saga with less imminent danger and peril all around them than what Jar Jar faced in the droid battle. But Jar Jar can bumble and goofball his way to effectively taking out droid soldiers and tanks as scores of less-incompetent Gungans lie dead all around him in his triumphant "WOO-HOO!" moment. Can the entire battle drama be undermined more effectively than that? Can there be a more insulting way to frame the struggle and sacrifice of the Rebels/Republic against a more formidable foe? And for what? For a laugh?
Jar Jar, and his goofily serendipitous triumphs, undermines the entire intended drama surrounding the struggle between the outnumbered "good guys" and the powerful "bad guys" in Star Wars. Jokes/humor is great in SW when it's simply an
accentuation of the storytelling; but when the joke actually
drives the storytelling and its outcomes, that's more sad than it is enjoyable. For me at least. Jar Jar was a joke (a bad one), and played the biggest role in turning that film (and the whole franchise at the time) into a joke.
We went from Biggs, Porkins, and many others dying while having no net positive tactical effect on their battlefield . . . to Jar Jar fumbling with bouncyball bombs, taking out droids and tanks with those, and coming out an unscathed hero. From tense battles and a depiction of the realistic sacrifices made in war, to a battlefield being the setup for a long-running punchline!
I fail to see how the Rose character is in any way whatsoever more damaging to the integrity of the larger story than the Jar Jar character was. I don't particularly like Rose either, but I just can't see how that character was a more pathetic and insulting waste of screen space than Jar Jar.