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.
First, "a million dollars isn't what it used to be". Say we had had a lottery in 1940? Tickets would probably have not cost a dollar as a dollar then had the value of a dime today. It would have a dime or nickel price and yield prizes in the tens or perhaps hundreds of thousands of dollars. Project that back even further and the numbers get even more rediculious by modern standards. If they never raised the price, they would still be selling tickets and having prizes at that level.
Second, at least in my state, and I suspect others, since the lottery is "off-budget" spending its own money without a tax appropriation from the legislature, it is a nest of triple and quadruple feather-bedded no-work political jobs. These keep the "cost of administration" very high, far higher than they would be even in a regular government program, let alone a private industry. Wages, etc, have certainly gone up many multiples since 1975 or so.
The ticket price jump was accompianied by a change in payout rates. I haven't had a chance to look that over in detail, but I suspect that overall the percentage being absorbed by the powerball system and the states has increased, and that is the real reason for the change. In other words, odds of winning went up, but not 2x.