I would say we have had good things, but they haven't quite hit the nail on the head. I mean, sure exploratory content was great, but the reality is this particular piece of content started initially in Heavensward with Diadem and had to be scrapped... Not once, but twice before we got something a little more flushed out with Eureka, and even then, personally, I don't think it offered a great deal until it came with the introduction of Logograms, and then Bozja really solidified the whole exploratory content, in terms of what it offered, but they essentially had to throw the entire kitchen sink at it to make it work as well as it did. - This pretty much reigns true for any piece of content. It's never been solid to start with really. Same with Island Sanctuary... I would say though, both Island Sanctuary and combat exploratory content could actually do with taking concepts from each other.
The thing to keep in mind is that it's always going to be a somewhat trial by fire. Budget and resources unfortunately are finite, so you aren't going to get something new without it coming at the expense of something else. This hits the nail harder than anything else, because then they still need to iterate through it, e.g., Pagos > Pyros. So it's like restarting the cycle of content development I guess.
I would say, placing this on a singular individual is a big mistake, as I don't think the issue is wholly on that one person. I don't think XIV gets the budget it really deserves, again, going back to the whole getting x must come at the expense of y - In an ideal world we would have gotten an exploratory zone in addition to everything we've gotten this expansion. With this in mind, I don't think it really matters who you actually put in that seat, to be honest. - Taking into account that they will still be under the same budgeting constraints and would still be developing for the same community, and we're a very divisive community. - You'll find as many people discontent with something such as exploratory content as to what there are people content with it. Similarly, you'll find just as many people discontent with relic grinds as there are people content with it. It's really not just as simple as a 1 person issue.
Dawntrail has given me things to be skeptically hopeful about, and a lot of it is around the interviews, etc., suggesting another exploration zone and a 'never before seen' piece of battle content. Based on this it does have the potential to be one of the most content-heavy expansions we've had... Now whether this potential does make it into reality is a different subject matter.
I think the best thing they need to learn is to reflect on older systems and to see what worked, and how it could be fed into newer systems, e.g., there is no reason why Variant/Criterion couldn't have borrowed a lot more duty actions from the Logos/Essences system.