I agree with Chocsosa. A watch should compliment a persons appearance. Sadly, a large percentage of people dress and wear watches as though they do not own a mirror. Short of maybe an NFL linebacker, I've rarely seen anyone that could carry off wearing a 45mm+ watch. There are even average guys wearing 44mm that resemble little kids wearing a watch from their Dad and they need to grow into it. But its a free country and if someone wants to follow the trend to the point of looking silly they are free to do it.
However, my pet peeve with extra large watches, is that so many are just an ordinary movement, from an ordinary company. Its frequently not from a great brand and it doesn't have complications that require the case be ridiculously large. If a person is going to wear something the size of a tuna can on their wrist, thereby drawing attention to themselves and their watch, it should be something from a very significant company, worthy of attention, and have a good reason for being so large, be it historic or an unusual/complicated movment that must be housed in an extra large case. To me, extra large/oversized watches which don't have any reason for being so large, are for posers caught up in the extra large watch trend.
It's hard to generalize about what compliments the appearance of people of different age, physique, subculture, etc. This debate reminds me of conservatism vs modernity debates that occur in every corner of Styleforum. Slim vs full silhouette, hard vs soft shoulders, country vs city colors, etc... The list goes on, and everyone tries to support their argument with a priori principles, but ultimately people wear what they like and if they execute the details well they hopefully accomplish their goals in the context they live in.
Living in Manhattan I see people of all sizes and shapes wear large watches all the time - especially Panerai and bulky dive watches. Many of them dress stylishly and their watches very much complement their energetic and sporty aura. For others, the watch plays a small role in their overall clumsy and awkward appearance. I also see some people who carry small watches with elegance, and others who just look like nerds.
As a general point, watch aficionados often overemphasize, arbitrarily, the aesthetic values of prior generations. Not to discount the value of seeing which designs have endured over time vs which trends became outmoded, but there's a lot of "glory days" thinking that parallels how people think about "rules" for formal attire and leads people to end up drifting far away from the mainstream for very little benefit. Right now there are plenty of people alive who bought watches from the 50s-60s when they were in production and not collectible antiques. In the not so distant future that will change and the people who run the world will have arisen at a time when there was hardly any consensus on the "correct" type or size of watch to wear, or whether it makes sense to wear a watch in the first place. Tangentially I think it's funny when people speculate on the investment value of current production watches - as if the regard today's kids have for Rolex or the "Big 3" will in any way resemble the current auction trends.