Well, nothing stopping me except the financial limits of what I can justify. I work hard for the money I make and there's a lot of world i've yet to see. I love theme parks, but if i'm going to spend a lot of money on a theme park vacation, i'd rather it be someplace like Tokyo at that point. It can be a cultural vacation first and a theme park vacation second.
Plus, Tokyo Disney is actually affordable. A 4-day pass to TDL and TDS is 22,400 Yen - or $208US. And if I really wanted to get crazy and travel to Hong Kong and Shanghai too, a 2-day HKDL pass is only $92US and a SHDL pass for as little as $47.88 for one day or $95.76 for THREE. That's potentially only $303 on park tickets to see worldwide parks for admission of NINE days(!), plus the chance to visit world class cities. I wouldn't even have to use all 9 of those park ticket days for me to find the worth in spending $300.
As great as Disneyland is (and it is great), there are other things I want to see in the world as well and i've already been to DLR three times. DL's pricing is just bonkers right now, quite frankly.