What drives a poor reputation for the Rogue class?

[Schwann145]

There's also the aspect that feats and class abilities often eat into skills, which creates the issue of 'no, you can't use your skill that way - you need this specific feat/ability to do that'.

For example, look at an Assassin ability:

Infiltration Expertise
Starting at 9th level, you can unfailingly create false identities for yourself. You must spend seven days and 25 gp to establish the history, profession, and affiliations for an identity. You can't establish an identity that belongs to someone else. For example, you might acquire appropriate clothing, letters of introduction, and official- looking certification to establish yourself as a member of a trading house from a remote city so you can insinuate yourself into the company of other wealthy merchants.

Thereafter, if you adopt the new identity as a disguise, other creatures believe you to be that person until given an obvious reason not to.

Surely this should just be a standard use of the Disguise and Forgery Kits?

I despise this sort of design because 1) Assassins end up stuck with the astonishing ability to use a disguise kit to... disguise themselves! 2) The ability to create disguises/personas of this nature is removed from other rogues, "because otherwise what would be the point of this ability?".

These abilities don't allow you to use the Disguise Kit and/or make Charisma(Deception) rolls, they make you so good at them that, in the vast majority of the time, you get to bypass those rolls (and the drawbacks that go along with rolling, such as opposed and passive checks).

A non-Assassin wants to make a disguise? They roll, using their Disguise Kit proficiency (assuming they have it; otherwise just a flat Attribute roll), and set the DC of their disguise, which is used going forward until they either succeed at their objective or until their disguise fails. Even so, it's possible your disguise is flawless but fails through different scrutiny; you didn't forge a background, establish relations, etc. You may "look the part" but fail to "check out" when investigated.
An Assassin gets to skip all of that, because their disguise is that much better than the non-Assassin's, and they "brought the receipts" for the background, relations, etc as well.

The Assassin's ability doesn't prevent the former in any way.

Neither version of Assassin has anything that makes it special; as stated above, 2014's false identity is foolproof until it isn't (and even when it is, what benefit that specifically gets you is vague at best)

It makes you immune to Passive Investigation/Perception checks; you never have to worry about them. And against Active Investigation/Perception checks, you get advantage on your Charisma(Deception) roll.
It's pretty clear what the advantage is, IMO, even if it isn't literally spelled out as such.

While we're on the topic of what a DM might allow, Xanathar's has this to say: "Advantage. If the use of a tool and the use of a skill both apply to a check, and a character is proficient with the tool and the skill, consider allowing the character to make the check with advantage. This simple benefit can go a long way toward encouraging players to pick up tool proficiencies."

So if disguise kit and Deception both apply, a DM might be giving you advantage anyways.

...and 2024's is rendered moot by the tool+skill=continual advantage rule.

Except this isn't a rule, it's a rule suggestion. Contrast to the Assassin abilities, which aren't suggestions: they're the subclass rules.
Yes, utilizing this suggestion would absolutely devalue abilities like Imposter, no argument. Just like utilizing the DMG's rule suggestion for flanking would seriously devalue things like the Shove maneuver and the Barbarian's Reckless Attack.