Lanefan
Victoria Rules
IME swarms are very rare (can't recall the last time I met one as a player, and have DMed maybe one in the last two years), constructs are fairly common, and undead are a near-constant.Here's the thing though, every game and every player's experience is different. I've faced lots of swarms (they suck in 3e) and my DM's often feel that the best solution to not having to explain a dungeon ecology is to fill it with constructs and undead. Adventures will use whatever critters make sense, and classic pre-written adventures tend to have a mix of monsters. So while you think swarms, constructs, and elementals are rare, they could be commonly used in a game.
That said, while I wouldn't allow backstrikes or sneak attacks against such things I would and always will allow criticals against them; the in-fiction rationale being that you happened to hit a key bit that holds the construct or physical undead together, or the heart of what animates an incorporeal undead, or the most concentrated part of the swarm.
I disagree. It's neutral design, and sometimes players just have to suck it up and accept that they might not have brought the right character for the job this time. 1e Illusionists vs undead - who are by and large immune to illusions - is the classic example; or a Druid in a dungeon crawl. This is the risk factor in the equation when it comes to playing a specialist character like this.Having those monsters exist as a flat-out bane to one class and not others is bad design,
The flip side is that there will be times when those same classes can tell the rest of the party to sit back and enjoy the fun as they wipe the floor with the dumb-as-rocks Ogres (Illusionist) or the woodland menaces (Druid). This is the reward factor.
Backstrike in 1e was too limited by RAW. Sneak attack in 3e-4e-5e is IMO far too generous; and the whole idea of Rogues as being the go-to primary damage dealers is IMO faulty. There's a middle ground there somewhere.So maybe in your experience there was value in the limitations on Sneak Attack, but I just didn't see it. It didn't help that Rogue also had no niche protection in 3.5, so you could easily replace one with a class that brought other kinds of utility to play, from Factotums to Skulks to Beguilers.