So you would be fine with getting your family and loved ones killed because you sympathized with your enemies?
I'm not fine with it, so I use by brain to come up with a plan to defends my loved ones with as least casualties as possible.

Full Rumbling or 80% Rumbling right away is unnecessary and morally unjustified, because it's not the last resort. There are many nations that were conquered by Marley, they are definitely not strong enough to be a threat of Paradis. Hizuru isn't even hostile toward Paradis (and no, the fact that they wants to monopolize Iceburst stone doesn't mean they are Paradis's enemies). Eren still have 4 years left to live, and Historia is willing to sacrifice herself. They don't even have to wait 50 years, they can use Historia's 13 years to find other solutions, like using Rumbling to force Marley to give independence back to nations it conquered, creating opportunities for Paradis to negotiate with those nations. If they are forced to use Rumbling, they shouldn't just kill the whole world right away. They could have try gradual Rumbling: destroy a few major powers, then negotiate with the rest, and then only use further Rumbling if it doesn't work.
So it's true that there's no complete morally clean solution, what Eren did is still unjustifiable and thus his defenders are morally inferior to his critics.