Possibly because if the clothes sit for an hour or two after the wash cycle ends, no problem, but if they do the same in the dryer, you end up with wrinkly clothes.

My current washing machine (new about 4 years ago) does. Fortunately, it's also got a volume option, including "off".

Hm. Our machines are about 15 years old (we bought the house shortly after I started working at UT, and I've been at UT 16 years). Maybe someday they will cease to function and we can replace them.

This assumes that you're not washing homemade tie-dye stuff. High-quality tie-dyes have the potential to bleed slightly for a surprising number of wash cycles, and if you leave them sitting wet in the washer, they'll bleed onto whatever is next to them. I've lost a couple of light-colored tops that way, and gained some interestingly-spotted underwear.

Because you're more likely to notice when the water gushes out onto the floor than when the hot air does?

That's better than my machines in which neither does.

As the drying cycle takes longer than the washing cycle, the dryer end-of-cycle alarm would be sufficient when doing multiple loads in my house.

What I find annoying is that both the washer and dryer supposedly give cycle times, but they aren't accurate. To be fair, the washer's cycle time is probably for the wash cycle, but not the rinse and spin cycles, but the dryer has no excuse.

My washer and dryer are out on a porch where I can't hear them anyways.
I set the oven timer as I come in.

I wish our washer didn't have one.

Because clothes can sit wet for half an hour without meaning you have to iron everything.

My dryer doesn't buzz.

Our Frigidaire washer beeps at cycle changes, including the end and the dryer buzzes when it enters cool down phase and every 10 minutes afterwards for 30 minutes to alert you that it is in fact, done.

mine does, and i'm eternally grateful for it!