Eclecticism

Someone suggested that Qitniyyot was a foolish custom day one so why bother? OK if Rema is in error let's ask the following questions re: deviations from Talmudic fundamentals:

1. Why mourn during Sefira?
2. Why observe Lag Ba'omer?
3. Why prohibit polygamy?
   

• Why do we not follow Talmudic mores in mourning e.g.
• Covering the head
• Turning over the bed
• Baring one's shoulder.

The Rema says that nonGlatt is acceptable. The mechabber R Y Karo who permis Qitniyyot has a very strict version of GLATT. Much stricter than American Glatt

So are those kvetching re: the "humra" of Glatt the same ones kvetching re: Qitniyyot? If so do they look for eclectic leniencies and favor every lenient position?