Not even Inside Out managed to get as mature as the original Toy Story. Still one of the best scenes in all of Pixar history, about knowing your limits and coming to terms with who you are (but not letting that hold you back).
The metaphor is strong with this one. Most meaningful/powerful scene in all their movies. I seriously doubt anything they do will ever match it. That scene is just a part of why Toy Story 1 is by FAR their best work.
No. TS1 ended on a light, to be continued note. So did TS2 (musical number). TS3 ended on a "it's all coming to an end, but that's ok" note that perfectly tied up all three movies and delivered a rare, satisfying conclusion to the trilogy. Way different.