Spoken about this before, but there are a few reasons 5e changes do not translate well at all to 3.5 ruleset. Even if they 'were' possible, it would be a problem.
1. The shorter duration is deliberate, to enforce buffing being a careful affair of consideration rather than fire and forget. In particular in DM events, it would make buffing a simple and singular affair. However, the crucial thing you are overlooking from 5e that is present in 3.5, is that in 5e only a SINGLE concentration spell can be maintained. No more. So, while it is frustrating to have a shorter duration, if you wanted 5e mechanics you would have to, say, choose -between- magic weapon and bulls strength. Not both.
2. I admit I love the less save or die effects in 5e. However 5e is limited in its counters, has a lower number DC over all, and saves are pretty good. 3.5 is a totally different animal full of many counter abilities to what you describe, including a blanket 'no death effect' lvl 4 spell.
3. I do tend to look at point 2 for this. But its also crucial to the server make up. Those attacks exist to encourage party play to have a full suite of counters. Maybe thats annoying, and frustrating, but its there for players to more or less be forced to party up. One of the reasons, anyway.
4. The crit multiplier thing is somewhat crucial to the game system because 5e works off a -very- limited number pool. AB, AC, are all lower and stats cannot pass 20, except in exceptional circumstances. This is offset in 3.5 due to the massively higher AC and AB numbers, not to mention a larger hit point pool. Much more in the way of feats as well, to offset it. Removing it also would make characters who are only good against living enemies extremely redundant. Its is, for example, the only thing a weapon master is good at.
5. Damage reduction becomes vital not to enemies but to -players- at later stages. Without ethereal visage, without stoneskin, and more besides you'd be far more upset than with enemies you haven't armed yourself correctly against. What you are talking about is entry level enemies. Its not a good suggestion to remove everything based on entry level mechanics.
6. Weapon finesse exists because unlike 5e, 3.5 is unlimited stats. You can have 30+ dexterity in 3.5, if you want, rather than the top score of 20 in 5e. Currently dexterity is tied to AC, and AB. Strength is tied to AB, and damage. However, if Dexterity was crucial to AC, AB, and damage, it would make next to no sense -not- to 'only' play a dexterity class build, for practically everyone. There would be no sane reason not to at that point, which is why it just does not work. Its immensely overpowered to put all of combat into one single stat. It works wonderfully in 5e I admit, but that is because of the stat total limitation amongst other things, not to mention the lower AC and AB totals overall. This change would need an outright massive overhaul of the entire game from base code up to be viable at all, and that isn't happening.
7. Rogues are in fact the single most successful class on the server. Particularly in the only field that actually matters, consequence wise - high stakes PvP. They're also masters of stealth, outright required for most dungeons due to their trap and lock abilities, and generally are the richest due to their incredible ninja looting abilities (something which the server is designed around encouraging btw, with its highly advanced looting mechanics that cause minimum impact for other players). The fact they can't one shot a skeleton isn't going to change the fact they're vital elsewhere.
