For me, and for a lot of other people, strong is fun. I enjoy coming up with new and interesting ways of beating the bad guys. Sometimes through my character build, sometimes through effective use of spells or combinations of spells, sometimes through using the environment against them, and occasionally through talking my way out of the fight.
Some editions make it easier to build overly effective characters (and conversely overly weak characters) by giving you so many options that you can find synergies no one intended (or combinations of abilities that sound good on the surface but really don't work together in practice). 3rd edition was like this, and Pathfinder is really like this.
5e gives you enough options to make strong characters, while still allowing non-optimized builds to be mostly viable.
Some editions make it easier to build overly effective characters (and conversely overly weak characters) by giving you so many options that you can find synergies no one intended (or combinations of abilities that sound good on the surface but really don't work together in practice). 3rd edition was like this, and Pathfinder is really like this.
5e gives you enough options to make strong characters, while still allowing non-optimized builds to be mostly viable.