But... pit traps are so classic!3.5ed broke down as more and more classes were added to it. The more you add to a game the more you risk it becoming broken.
What I hope is that 5ed does not fall into that pit trap too.
I assume you're referring to 3.5 and it's Tier 1 classes being right in the PH1, most notoriously, the core-only CoDzilla.The core book already had the Wizard and Cleric classes.
Though, obviously, 5e also has the Wizard & Cleric - and Druid - and it's really adding spells that might open up broken combos or be easily abused by neo-Vancian casting mechanics, rather than adding classes, that's the danger. Especially as the multi-classing that made new classes & PrCs contribute to broken combos are as optional as the new classes, themselves, this time around.