Hello, Beau!
First allow me to welcome you to the Playing Card Forum. If you're interested in remaining as a member, please head over to the Introduce Yourself board and start a topic - we'd like to learn more about you and give you a proper greeting!
Second, yes, I'm opinionated, many people are as well - but they're opinions. Not every word out of my mouth gets etched in stone and painted with gold. We're opinionated because we really enjoy our hobby!
If you're counting the "I'm talking about this idea with people" stage, hell, some of these decks have been a decade or more in the making! But you stated it more like the actual pen-to-tablet period was two years, which is why we sound a bit incredulous. LoTrek - whom we love as an artist and designer - was hip-deep in his own card designs two years ago!
Moire effects are liked by some, but not so much like others - your marmite comparison is very apt. It's also a bit dated, having peaked in popularity in the 1960s. A better idea for card design is to use a design that's attractive but not distracting - decks like the Fontaine are popular with cardists because they're simple, classic and "plain enough" to not pull the audience focus off of the cardistry and on to the cards. But there's been a lot of them lately, so yes, I agree with you that they can be a bit overblown and boring. The one exception would be a plain design based off a more complex one - examples of this would be the new Whispering Imps Gamesters and the Zen decks originally sold by the Conjuring Arts Research Center (
CARC)
There actually is a growing trend these days for plainer designs. Old school, simple and attractive - and less expensive as well, because they're more for use than for collecting and thus have few to no bells and whistles added on.
You mentioned trends that were getting a bit tired. Modding the courts to look like family and friends is one of those trends, as is making unusual custom pips (though I'll grant you that yours are plainer than some). Making the courts wholly unique rather than modifying the classic courts works better - one of the best examples of this is the WhiteKnuckle deck; though they're hard to find these days the designer's website is still online. Using a simpler modding process almost invariably ends up with a mis-fit in terms of scale - humans have a proper, recognizable scale while the classic courts really don't. Better to start from scratch and really make the courts your own.
Blank face courts have been used in a few decks, some examples being the Bicycle Clot Ltd. Edition and the Mystery deck from BeDeceived (now defunct). And letting a random, big-ticket backer be on a court card can really create hassles - you never know who's going to win and how fussy they're going to be about how they're represented. An ego boost sounds like a fun reward, but it really can backfire like a too-short sawed-off shotgun.
As far as the gaff card - it's a take it or leave it, really. Duplicate cards are useful for magic - but is this a magician's deck? As a working magician, I learned a couple of years ago that using expensive custom decks when performing is NOT a great idea. They get manhandled and grubby in no time - to you, a custom deck is a rare collectible while to your audience it's "I can get these for a couple of bucks at the newsstand!" They don't see cards as rare or expensive and thus don't treat them as such. The cards I carry - even the trick decks, when possible - are common and inexpensive, or at least not too costly.
In addition to this, a magician is inclined to use a deck the audience will identify with - the closer to a classic card design, the better. It's not that they think the cards are a trick deck, but it gives them that comfort factor - "Oh, this is OK, I have cards like this at home." Put them at ease as much as possible and you'd be amazed at what you can get away with right in front of them.
For these reasons, the duplicate card isn't entirely necessary. You could try an innovation I've seen once before that I don't see often enough - the Spare card. The Hornets from Circle City Card Co. (now out of business) had an extra card which could be used as a substitute for any card lost or destroyed in the deck, complete with boxes for filling in pip symbols. It was pretty sweet, and positions your deck as a deck for players as well as whomever else you're targeting.
Cheers and good luck with your project. While it's not to my tastes, I'm not the final arbiter of taste!