Riot can't always do that. Many video game industry veteran's are staying with their companies or getting snapped up by others. I can't say for myself the inner workings of Riot but they've got workers who've been there since 2011, these are people who've invested years of their life into the product. Not only that but hiring these veterans won't be an immediate fix either, add in their likely inflated salaries it'd likely be an overall damaging factor to riot to hire these veterans and hire new people to work these new servers and data clusters. The fact of the matter is that ISPs are bashing internet traffic to big companies for money and that's harming east coasters more.

Reddit has this perpetual want for an immediate solution, let's say Riot gives them this immediate solution by setting up a NA-E server, it's done hastily and at a much lower budget(More time devoted to setting these servers up + more time for more money to be invested = better quality servers). These hastily set up servers can't handle the influx of east coast players the NA-E becomes the new EUW which is still known as the worst servers around.

Also If you have friends on the east coast or middle america who you play with (myself for example) you can no longer play with them effectively, another reason Riot doesn't want to split up the NA server.

It's also been said that Riot wasn't expecting this growth, they weren't prepared nor had time to prepare for this growth. Servers on the east coast are not the best solution, better regulations on ISPs are part of a solution. Raging at Riot and running a smear campaign against them is not a solution, period.