I find it funny when FFXI players in here mention they jumped to here because Abyssea and SoA ruined everything then find disappointment that this game isn't what they wanted either and say it needs to be FFXI. I love FFXI as much as the next person, but why are you trying to completely change FFXIV into something it is not? Why are you not on the FFXI forums complaining you want the old day game play back? You get frustrated at FFXI and take it out on FFXIV. Just because this game is called Final Fantasy also doesn't mean it is obligated to use concepts of it's predecessor.
Your main issue when making "very deep and complex mechanics" for a job itself, it is the first step of creating a major imbalance. Don't believe me? Ask 3/4 of the jobs in FFXI that don't get invited to parties because a job with mechanics you are seeking gets ignored for more convenient, simple, and more efficient jobs to play. That was a real bummer to me and I feel like I have to force myself to play something I don't just to get more frequent party invites. This has been an issue in FFXI since advanced jobs became a thing and it hasn't been fixed since. In FFXIV, if you make it that you are more focused on your bar than the fight itself, something went wrong in it's design and good luck dodging things while performing efficient DPS.
I have actually been trying FFXI again to see what has changed and what is new. While I am having fun playing around on THF, I got unfortunate news that if I continue it, it will only come with hardships in joining groups. This issue is near non-existent in FFXIV. Why? Because it bases itself off of simplicity in job mechanics and lets the fights and environment around you be the complexity itself. My example is a different genre but still has a point. Super Mario Bros., all you need to learn is that "A" is to jump, and you can hold down "B" to move faster. Simple to learn right? How to play, yes. Now can the average person take on The Lost Levels(SMB2 in JP) and beat it? No, its very difficult because the level itself and not your controls and concepts. FFXIV runs under a similar concept that it depends on what is around you to determine the difficulty, not necessarily how well you build yourself up. Even then FFXIV still has some complexity in it's rotations and priorities. Go look at any guide here and there is much more to being efficient than hitting 1-2-3 and some buffs.
If you don't like that style and prefer FFXI's, its fine, its not necessarily better or worse, it is different and the game can be difficult in it's own way. I know I had some hair pulling moments in my 2003-2010 career. At the same time however, you have to realize that a lot of FFXI's concepts and mechanics simply do not work in this game. It can be held up to interpretation when expansions come and change things around, but I doubt ARR would ever change drastically to the point that overly complex pet or elemental systems would make it's way in there.
Find ways to make what is already in FFXIV now better without tearing down the wall and putting up something new. Unless proven broken, Dev's will listen to constructive criticism first before destructive criticism. I have my list of complaints with the game, but I wouldn't ever ask them to tear things down to just meet my own interest. I love that the game uses WoW as a blueprint to make it's own game while still bringing new things in. FFXIV has enough of it's own concepts and beautiful world with a rich story/lore that in my opinion to stand out greatly from other typical MMO's. I was actually hoping 1.xx was like this and we got well.....that.
FFXI and FFXIV are two completely different games. It was intentional by the developers. Play the one you prefer more, one is not truly better than the other at the end of the day. FFXI may feel out of date here and there, but still a great experience to play. Or maybe it is just nostalgia kicking in there.