Yup, costs went up. We're in a really bad place right now economy wise where the Consumer Price Index has gone drastically up for the last 30 years with only a small blip around 2009 when the market dived. Usually this is okay because as the cost of goods goes up, business owners also take in more cash and have more money to spend, companies pay more, and salaries increase.
Bad news time: U.S. wage/salaries are flat. Last year marked the first time we saw a slight increase on the average salary in almost a decade. It still was well below the traditional trend and it is not enough to correct purchasing power. There are less small business owners and more employees at companies that are doing 1 of 2 things: stockpiling cash to survive when another 2008 hits, or paying executives larger salaries.
So you're asking, why did the cost of a ticket to Disney parks go up? And how does the change in CPI effect you? Simple supply and demand. As has been noted in many places, the parks are beyond capacity on a daily basis, the reports of slammed September are true. I remember the days when sept. brought cast members stopping to say hi in the parks and wishing you a magical day. They are long gone. Replaced by a surge in international visitors(they always existed, just not to the current magnitude). And during the summer the parks were so crowded I often felt unsafe traversing main street/castle hub during parades/post fireworks/etc. So Disney has two options:
1. Build more.
2. Raise prices to thin out the crowds and obviously maximize on the opportunity.
Simply adding capacity isn't really plausible in the short term nor sustainable in the long run. Building takes time, yes the original construction time was short for both Land and MK but construction with a blank canvas, no crowding, and states/counties rolling out the red carpet for you make it very easy. These days supply chains are strained in the central florida area, many construction firms are having problems getting qualified subs, and the planning process is much different from the 70's. Compound that with the need to continue operating in the area during expansion and it wont be quick. In the event another economic downturn to the tune of 911 or 08/09 happened, more expansion would mean more financial risk.(Not saying they can't handle it, but Disney has ALWAYS been conservative when it comes to risk exposure and it has paid off)
So the company raised prices. Everyone seems to be hung up on the increased profits they get from this. Meh, companies exist to turn profits and they can't build giant expansions without it. Sure, you're paying for it before it's built, but why get a loan when your customer base supports an increase?