On Quetzalcoatl, at least, there's a fierce debate over which windower plugins are necessary conveniences and which are cheating. If we want to get technical, even the windower itself is technically against the rules, but even someone as anal as me can't find it in me to hold that against someone.
Added to windower were eventually plugins like Tparty which displays alliance mp and other players' TP and what not. I don't know the specifics because I'm not using a windower. Alliance MP I thought was a good idea. I wish I had access to that info, even though I won't do so. Party TP, I think this is a bad idea. Back when the plugin was released, I was a PS2 user. I'm also a Blm. Tparty destroyed paty communication. I either had to forgo magic bursting, or forgo any early battle enfeebling of any sort, because psychic melees initiated skillchains silently. Rare was the melee who was willing to revert to party communication for the sake of the blm. Still, I didn't think this was cheating worth fighting against. I just thought this furthered the mage/melee and PC/console divides. Since I could manaburn anyway, I was happy to let the "Cntrl A and AFK" jobs do their thing. This plugin is on the line, as far as I'm concerned.
The Range plugin made rangers and bards fairly skillless jobs. I learned to guage the radius of my aga spells. Other jobs should have to do likewise. There isn't much skill in FFXI. I do think it's cheating for a few jobs to opt out of the only thing close to thinking their job has. I guess rangers wanted to be as mindless as monks. It's not like you can autoattack ranged attacks anyway. They might as well spend some time concentrating or something, if they have to be pressing buttons anyway. This plugin I do think crosses the line.
Now they have plugins to automatically sort your equipment and lot crap while you're dead. The former seems harmless but the latter is clearly cheating. The lengths people will go to defend their poor gaming is astounding.
A lot of people say SE should've given us more macro lines from the start, and feel justified making catchall super macros with their billion lines and fancy coding. A new plugin even automatically accounts for weather and whatnot. SE "should've" done a lot of things, but they didn't. I think these are squarely cheating too.
I'm beginning to think the definition of cheating is whether or not windower endorses it. For example, voke bots and fleehacking isn't a windower plugin yet, so those are condemned. Self adjusting, programmable super macros, lotting while dead, and AOE gauges are supported by windower, so they're kosher. I think windower should make voke bot plugins and fleehack plugins so that the population will either turn on the use of plugins in general, or stop being hypocrites in terms of what's cheating and what isn't. "Anything I don't use is a cheat" isn't the definition of cheating, but in FFXI, it seems to be.