JP side started a thread Why is FF14 for light user? (Casual Players) just like our thread in the US. They got a response so here goes.

Original Thread Link: http://forum.square-enix.com/ffxiv/threads/15380

Quote Originally Posted by Mocchi View Post
こんにちは。
Hello,

カジュアルという言葉に対して誤解があるようですので、今一度、第12回プロデューサーレターをご確認ください。
There may be misunderstanding for the term 'casual' please re-check the 12th producer letter.

In order to keep up with the times and cater to changing lifestyles, large-scale MMORPGs such as FINAL FANTASY XIV need to offer a more casual playing experience than before. Mind you, that’s not to say that the entire game should be casual. Rather, there should be elements that can be enjoyed in a lighthearted way, for example, after coming home tired from work or school, with mobile phone or refreshing beverage in hand. To elaborate, content that can be enjoyed with little fuss, that doesn’t demand large time investments—up to an hour, say—or require a party to be formed.

But come weekend, players have the choice of undertaking more elaborate adventuring, forming parties with linkshell members and/or likeminded adventurers to accomplish mutual goals. Light parties can exploit the versatility offered by classes to conduct forays into beast tribe settlements, something that a lone adventurer would find grueling. Full parties, on the other hand, can immerse themselves in fine-tuning job configuration in preparation for their bid to obtain rare items in advanced battle content. Disciples of the Hand can outfit the battle-inclined with equipment boasting the requested attributes. And last but not least, Disciples of the Land can set about gathering ingredients based on current class and materia crafting demands.
(I put in the English Producer Letter 12)

FFXIVがカジュアルゲームになるかというとそうではなく、カジュアルに遊ぶことも選択できるゲームにするということです。
It doesn't mean FFXIV is going to be casual or not, but a game where you can also choose to play casually.

今日は仕事で疲れて帰ってきたからカジュアルにちょっとだけ遊びたい、土日は思いっきりヘビーにプレイしたい、その両方のプレイスタイルを提供することを目的にしていますので、どちらか一方向のゲームになるということではありません。
We are aiming to provide where you can come back from work and play casually little bit, or doing heavy play during the weekends. It does not mean it's going to be one side or the other.