Why should I get DVD movies if I already have these movies on VHS?

personally I think it's a horrible waste what people are doing, throwing out their VHS tapes and re-buying all their movies on DVD. what's next? throw out all your DVDs when blu-ray becomes more mainstream? I will continue to use my VHS tapes till they wear out. I really don't care that they are "Obsolete" I'll get the movies on DVD as my tapes wear out, but by that time DVDs might be obsolete too... my tapes are in great shape. quality is not an issue for me. people are too spoiled these days. what do you think?