Why all websites and apps should be HTTPS?

Hyper Text Transfer Protocol Secure (HTTPS) is the secure version of HTTP, the protocol over which data is sent between browser and the website. The 'S' of HTTPS stands for 'Secure'. That mean the communication is encrypted. Web browsers Internet Explorer, Firefox and Chrome also display a padlock icon in the address bar which indicate that a HTTPS connection is in effect.There are some complains that HTTP is better than HTTPS for few factors like HTTPS is slower than HTTP.

Do you think HTTPS can totally safe guard?