Well if you think about it, the standard lottery ticket has been $1 since your state started having a lottery, which could be as long ago as the late 60s. Simple inflationairy pressures apply.
The real deal is that there used to be two state groups for lottery. Thirty-some states, most smaller states, had Powerball and twelve-odd high population states had Mega Millions. They merged in 2010, which meant that they had two games that were pretty much the same overlapping. (For legal reasons California remains the only state to offer only Mega Millions and Florida offers only Powerball). So this is an attempt to differentiate the two games.