This poll is a bit misleading MaRo, the asker said that the current ratio is disliked, not that there shouldn't be a mix at all. And also the answer C of "a healthy mix" is poorly defined what that ratio should be. Imagine if your audience primarily defined C) as "every walker outside the gatewatch should be from this plane", but you defined it as 50/50. Both you and your audience would expect the answer to be C, but you would still wholly miss that you are off base. If you had just left off C you would have gotten a more clear view of your audience's desires. To be fair to you, the asker was also unclear and hyperbolic.
However, to illustrate the asker's intended question, I went and gathered the information on the trend I personally have seen.
Looking at planes alone: This is where the trend is completely clear and this is what I think a subset of your audience finds frustrating. Eldraine, Ixalan, Amonket, Kaladesh, and Innistrad to boot, Five of the last Eight standard legal, non core planes have had one or more walkers from, on, and introduced in that plane. Furthermote Eldrane, Dominaria, Ravnica, Innistrad, and Zendikar were all homecomings for one or more walkers. Meaning every single plane, (and all but three non-core sets: AKH, AER, and EMN) we've been to since the major block change has had a walker from it, in it.
Looking at walker introductions specifically: This is more mixed as there are a dozen different ways to collect your data. I choose to exclude core sets and supplemental sets from the previous data because they frequently don't have a clear plane or a wealth of story, but this leaves a lot of grey area: walkers first introduced in supplemental sets or core sets that also made it into non core standard legal stories. Specifically Kaya, Nahiri, the Kenriths, Vivian, and kinda Ob Nixilis. Of these, if we ignore their previous introductions, the only the Kenriths were directly "introduced" on their home plane. Discounting those special cases there have been Eleven planeswalkers introduced in non-core standard legal sets. Six of those were introduced in and on their home plane. The odds go to Six out of Seven if you drop the four introduced in WAR, all of which have less story, smaller impact cards, and come from a set that beautifully bucks all the trends that magic had fallen into since Tarkir.
The greatest problem of this is that the sets are all extraordinarily similar in structure from a card standpoint and it seems that introducing a planeswalker from a plane other than the current plane is becoming the exception, rather than the norm or even a common occurence, which arguably means that you do not have a "healthy mix" going.
Now there is no doubt that all of these trends are far more muddled and mostly disappear when you include supplemental sets, but those are not your flagship sets, your driving story or your major focus. This really irks people who actually follow your stories but it also irks people who follow the trail of your story but mostly pay attention to the cards. Planeswalkers are planeswalkers, they go from plane to plane, and they only find out they are planeswalkers by leaving their home plane (excepting Huatli), they are excellent at being fish out of water, but they are also amazing as people who found their perfect home.