The idea that we cannot confirm the effects of the outer planets because they have not been known about long enough to complete enough transits (and none in the case of Pluto) doesn't really hold water.
Part of astrological research is in looking back through the major events in history and exploring the relationship between the stars and those events.
One thing I think is important to remember is that the influence of outer planets, and other bodies, can be both generational and personal, in the same way that the Sun warms one whole side of the earth at any given moment, but also warms and affects individuals at the same time - it's the same sun, and it's effecting everyone, but some people have conditions making it harmful to them, some aren't hydrated enough, and some people are just configured in that moment to feel recharged and refreshed. Someone will look at the sunrise or the sunset at just the right moment and feel inspired or moved emotionally. Just one light, it's the same light to everyone, but it's different to everyone as well.
By looking at history and understanding the effect of the outer spheres on the generations, we can then infer what effect it then has on individuals, even in signs that it has not transited through since we were aware of it - as above, so below; how it affects the individual will be reflective of how it affects the whole, and I think this is where most of the interpretations of pluto probably come from.
With the right conditions in support of one another, even the weakest application of energy can yield powerful force. I don't personally hold the idea that the planets have any effect on us electromagnetically - the natural forces don't operate like that, and if it were true then anyone born too close to the wrong kind of electronics or technology would have an invalidated natal chart. I fall on the "spiritual mechanics" side of that debate, and under this paradigm actual time and space are irrelevant - everything in the universe is exerting influence on everything else all of the time.
I believe that the faster cycles are more obvious and therefore we say that they are more prominent or personal. Just as we say that a person grows up faster than a tree, a puppy grows up faster than a baby. Different cycles, faster and slower. Slow cycles may not make for as wild a ride so you can more clearly see the ups and downs - but the rest of the cycles still take place in context to it and from different angles of operation, altering the bumpiness of those faster and wilder rides.
If you prefer a purely scientific approach to astrology involving the strength and weakness of actual rays of light, then probably best to give up astrology rather than ignore the obvious flaws in that quack science - if that theory is true (and there's no reason it needs to be other than so that atheists can also enjoy astrology) then it should be no problem to create a machine which will mimic the proper electromagnetic signature necessary to birth whatever kind of person we want to, right?
peace
....at which point people start pulling semantics games and throwing up smokescreens...there's definitely something to Uranian astrology though.
.