Why has amplifier power become a big issue

Nothing has changed except awareness that many speakers have not been driven to full potential over the years due to use with commercial gear like receivers and cheaper integrated amps without enough muscle to get the absolute most out of most modern speakers that tend to be smaller but retain low end extension meaning more current and beefier amps needed.     Usually the smaller and more extended a speaker the more the burden falls on the amp to make things click to the max. 

Tomcy6 speaks truth. 

Erika I learned that lesson early back then as well. 

Also that the larger amps in any particular line ALWAYS sounded better.    Not even just with the biggest thirstiest speakers that needed them most. 

Modern Class D amps are very efficient and solve the problem nicely.    Without them I'd be more prone to go tube amp (not efficient generally) and high efficiency speakers to pick up the slack there.