>>42282333 (OP)Because G1/G2 is more Spiritual.
That's really the core of it. G1/G2 is an odd era because it's willing to
(A) Explore harsh and complex emotions, which can be entangled in horrifying situations.
(B)Has a very strange thread of spirituality running through it.
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G4 is superior to G1 and G2 in many ways, but we can sum it up that ultimately G4 has a better handle on Music, Storytelling and Characters.
What G4 lacks, however, is the spirituality and harsh emotions G1 & G2 have. G4 will have these focuses in *spots*, especially in seasons 1&2 (examples: Canterlot Wedding, Feeling Pinkie Keen, Return of Harmony. )
(Twilights Kingdom is a good example of a later episode dealing with these emotional themes, but is crippled from Hasbro interference and poor storytelling choices)
G4 seasons 1&2 handling of emotional introspection are close to G1 generally, but quickly drifts away from that as time goes on.
When G4 really starts to lose the plot is when Haber tries to make it into a marvel rip off. This results in a kind of bastardized Shoujo. The focus in magic becomes replaced with a focus on "action".