Values and Cultures

It's still in the CNY seasons,,, And here's another 'WHY' question that has been bugging me.

"WHY do people practice certain custom/ superstition?"

Just a few years back, my mum shared with me that we should not buy shoes during the first month of the new year... REALLY? EVEN IF THE STORE IS OFFERING 90% OFFER?!?!??! Yeah... That's my response... And later with the help of Sinsei Google, I found out it's because the Chinese word 'shoe' (hai) is similar to the Cantonese word 'rough', or the sound of the sigh. And rough and sigh is filled with negativity.

Next, it's the famous 'Don't sweep floor on the first day of CNY' as it is believed that we will sweep away the luck from our house. Hmmm... How about vacuuming the floor and keeping the dust? Does that count? Or if it is really sweeping away luck, then why not not sweep the floor throughout the whole year? (Yay?)

And as I Google, I found more and more superstitions...
Don't wash your hair on the first 3 days of CNY (Gosh! I would have been grumpy if I had oily hair!!!) 
And don't break stuff on CNY (Who would have purposely break stuff on any day? Are we capable of stopping all accidents?) 
Don't use knife or anything sharp (How about food preparation?)  
Don't buy books (Books (shu) in Chinese sounds like losing, and so it is to be avoided... Hmmm... Can I suggest that knowledge might be more effective in reducing loss?)

And the list goes on...
If we are to avoid everything with similar sounds with some not so pleasant words, maybe one day we will be left with nothing to do... Somehow in me, I will like to believe that there are more appropriate values behind all these cultures, which perhaps are not handed down with the actions? Why should we follow customs which does not have any value in it? Why should we follow superstitions?

My thought on the no sweeping thing:
Maybe this culture came up to give our mothers a day of rest? If that's the case, i think it's valid, and make sense, and I will probably follow the custom... If it's for the luck thing, I am doubtful.

Or for the shoe thing:
Maybe it's because we have spent money to buy new shoes before CNY and so we should not spent unnecessary money on another pair of shoe?

Then it will come to another custom... Why should we buy a new set of clothes (and everything else) before CNY? We don't practice it for the Western calender...

Hmmm... Why?