It isn't a matter of being made of sturdier stuff. It's about some silliness and stupidity that used to happen in 1st/2nd edition. Don't get me wrong, there was more "personality" in the old versions of the spells.
However, it was pretty much a ritual to watch the first time someone played a wizard, they'd have no idea that fireball expanded to fill the space and end up killing themselves and likely most of the party with their first fireball. Then, after starting the campaign over again, they'd likely kill themselves with the second fireball they cast as they wouldn't understand the rules on HOW fireball expanded or get the math wrong and still end up killing themselves and the rest of the party.
Pretty much the same with lightning bolt. I can still remember the look on whichever one of our DMs was running the game's face when the newbie wizard says "I cast a lightning bolt, I hit all the enemies in the 20x20 room." when the lightning bolt then bounced off the wall, hit all the party members, bounced off the wall again, hit all the party members a second time and then stopped before it hit the enemies again.
There was a really large learning curve to play a wizard in the old editions because of this. Memorizing and remembering the quirks of each spell took a lot of effort that a lot of people weren't willing to do after their first experience like this. It also took its toll on the DM who ALSO had to remember these things AND do the math each time they were cast.
I, personally, prefer "oh, it's a 20 ft spread, it works the same way as all other spreads, it effects these people right here" instead of having to say "wait, it's a FIREBALL, so it fills the area" or "I'm going to rule that THIS spell doesn't go around the cover unlike other spells."
All the rules are the same instead of them being different for each spell.