I don't wear lycra shorts except for the hottest days in summer but I like bike specific clothing, or at least outdoor clothing, it's just more comfortable. I normally wear MTB shorts. I tried wearing regular shorts but some are just too uncomfortable: seams in the wrong places, stiff, etc. Sometimes I wear hiking shorts or beach shorts. And jeans in heat or rain are a torture. I don't even wear jeans shorts when walking in Summer.

In cold weather I wear warm, unpadded bike tights with the MTB shorts over them.

Normal clothing designed for slow walking doesn't work very well for cycling, even if it's just a 30 minute commute.

Perhaps if my bike riding was limited only to commuting I wouldn't buy any special clothing. Since I also ride longer rides on weekends and got into touring this year I need better clothing anyway. And a lot of it can be used for hiking as well.