What makes a “softshell” pant more weather resisant?

Maybe a good dwr and a thicker fabric that does not wet out as easily as thin fabric.

Softshells without membrains like you marmots may not be any more wind or water resistant, or even more durable (depending on use, stretch wovens tend to snag more than flat nylon). They should breath very well and allow for better mobility.

I use thin softshell pants in hot weather and am fine… but for me they excel in the snow. Certain woven softshells that tend to have smoother fabrics will shed snow with ease and not wet out unless there is pressure to force the moisture through (seat and knees usually). Even after the DWR wears off, the tighter woven fabrics just keep shedding snow better than nylon. I assume it is the knit… really don't know, I just know they work really well for high exertion activities in the cold.
I can manage internal and external moisture very well in stretch woven softshells with smooth fabrics.

Nothing

Softshells can be worse in wet enviroments as they tend to be thicker and absorb more water

The advantage of the softshell is its breathability and abrasion resistance

The water resistance depends on the DWR

;)

+1 to what Eric said.

When it's cold and DRY, soft shells are fine. They are nice during high exursion activities in cold, DRY, conditions. Especially when I take a break, they insulate better and still cut the edge off. One of my favorite pieces is a 1st generation TNF Windstopper fleece hoody. I wear it all the time in the shoulder seasons.

But in freezing rain, or in HUMID conditions with a threat of wet snow, they would suck. (Unless used under something more waterproof.)

schoeller dryskin and its lighter sibling dynamic, are amazing (magic) fabrics. dryskin for the most part isn’t compromised by the negatives listed above. Do a little googling or read the reviews on the rei acme pants http://www.rei.com/product/786840/rei-acme-pants-mens-32-inseam#tab-reviews . if i could only keep two pairs of pants in my wardrobe (and not just for outdoor activities) one would be my old rei mistral in dynamic and the other would be my acme in dryskin. both regularly show up in sales forums and on ebay and can be bought for under $50.

Thin unlined softshells are perfect for wet environments. Don't absorb water as readily as nylon, they're more breathable, and dry more quickly when they do get wet.
Don't think they're any more wind resistant than nylon, though.
One of my favorite things about softshells is that nothing wants to stick to them. Haven't used nylon in snow, but I've gotten it muddy plenty of times. Mud cakes, dries, and leaves stains after its gone. Dirt, dried mud, snow, etc. seem to just fall of the softshell material. When the nylon is still damp and grimy, the softshell is dry and relatively clean.

I've been using the Marmot Scree pant and OR Ferrosi hoody for years, and love them.
The Scree pants are too warm for use when the temps rise, and I've been using nylon Marmot Cruz pants and shorts for hot weather, also for several years. I was between sizes when I bought them, but have dropped in size since, and am probably going to replace the pants with the OR Ferrosi, which is a thinner softshell than my Screes.
I have some Eddie Bauer pants that are fairly similar to the Ferrosi, but also in a size I don't wear any more. They get used interchangeably with the Cruz pants in summer when I want protection for my legs. There's usually not a notable difference, but I like the stretchy softshells, and find them more comfortable and breathable.

Thanks for the info guys. It sounds like the idea that softshell pants are a winter ready pant is a bit of hype. I have some softshell pants and I was basically wondering if there was any advantage to them over my shorts/running tights/wind pants/waterproof pants combo other than durability.

The softshell pants I own are the marmot orion pants. I bought them for bushwacking around the central coast in winter. I read a review where a guy bushwhacked through Alaska for 20 days in them with no issues. I haven't had a chance to use them yet but I like slim fit for not catching onto stuff and the stretch for vaulting over logs. They really feel like a pair of stretchy tights in a durable pant.

They're basically for conditions when shorts are generally too cold for hiking in. They give you the wind protection of windpants with MUCH higher breathability and comfort (doesn't stick to the skin). You also don't have to mess with windpants as a layer. However, they do absorb more water and don't dry as quickly as thin nylon, but I'll still take them almost any day over nylon pants. They also keep you warm enough in a light rain that you don't have to mess with rain pants. The stretch-weave gives them the wind resistance with higher breathability over nylon pants. The DWR gives them water resistance. The thickness of the material gives you better comfort in light rains over nylon pants. In heavier rains, you'll want to wear rain protection still.

I think they are usually recommended for winter – but not because they are more water resistant. They are just nicer to hike and climb in. Softshells are often micro-fleece lined and warm enough with just a thin pair of "wicking" long johns. The alternative is to wear a 2nd pair of mid weight long johns, and wind pants. Less bulky and stretchy is nicer when hiking in steep rocky terrain and lifting your leg 18" a lot. Hard shell rain pants are needed in cold rain, even with soft shell pants.