Unless I'm reading that wrong, are you saying Jill wasn't wearing an irrational choice of clothing?
Right. She was wearing a boobtube and a skirt! In the middle of a zombie outbreak no less. Where was the reason in that? She could have easily been wearing her S.T.A.R.s uniform, but nooo. Let's dress her up as a hooker to fight an army of undead flesh-eaters. Flesh. Eaters.
You're lying to yourself if you're saying she wasn't put into that choice of clothing purely for fan service and eye candy.
Probably because the outbreak occured out of nowhere in Raccoon City, perchance? She also wasn't part of S.T.A.R.S anymore, it was effectively abandoned after the Mansion Incident. We can argue back and forth of what can be considered acceptable fashion sense, but there's nothing wrong with wearing a skirt, blue tanktop and high-heel boots when you're a civillian, which she pretty much was at the time.
Let it be known that I don't exactly consider Capcom to be effectively subtle about their game character designs. Ada Wong runs around in impractical high-heels and a skirt in RE4 instance, but it's acceptable because the game (doesn't take itself too seriously) and plays more along the lines with a sense of ironic retro campyness. It's still dumb though in a similar fashion to how Zero-Suit Samus is dumb.
Post-RE4, Jill always have zipper up, even in combat-gear, for cleavage points. This wasn't the case before and thus it's more noticeable and annoying.
The point was about objectification, which relates to how female characters are deliberately derived of agency and personality and replaced with nothing but sexualized husks. Jill becomes entirely dependent upon her male counterparts having to save throughout all of the games, and this is especially the case in RE5, where it feels more or less like she can't do anything without a dudebro to pick her up. This is Capcom, however, it's always been like that but now it's become a bit more obvious. The tank top isn't exactly o-inspiring either .. I can dig tanktops just fine as long as it doesn't come off as an obvious stunt to fetishize, like Faith in Mirror's Edge or Lara in Tomb Raider Reboot. Hideo Kojima sexualises most of his female characters, but it's never at the expense of any agency, thus the intention is never to objectify, but that's not to say it isn't annoying sometimes, which it is. Looking back at MGS1, I can't help but facepalm over the fact that the few female characters there are in the game are dressing quite inappropriately for an otherwise harsh and cold environment.