Bitcoins are good as they are now, I wouldn't change anything. I think over time everything is going to be fixed and transactions will be much faster. Normally there is problems with bitcoins, but every currency have some flaws. I don't think those flaws are so big that I can say that I hate bitcoins for that, simply I like bitcoin in this current shape.
But i think why people still hate bitcoin , because bitcoin is digital currency you can't hold it unlike physical currency (flat currency)
Or they got scammed with internet investment , and stay away about internet money making so automatically they also hate bitcoin.