That is totally wrong way to look at it. If in early 2000s Hewitt, Safin, Nalbandian and Roddick managed to challenge Federer - it would have been "strong" era, but because they didn't - it is a weak era. If players like Del Potro (he actually has an excuse due to brutal injury to the wrist), Berdych, Cilic, Gasquet, Tsonga, Murray managed to archive higher peak - late 2000s and early 2010s would have been a strong era. And then there were Tsitsipas, Thiem, Zverev, Medvedev, Dimitrov, etc... If they managed to do something we would have another illusion of time of great champions. The reason why there is no big number of champions since early 2000s are Federer, Nadal and Djokovic. Only Wawrinka and Murray are multi-slam champions since big3 era started (end of 2011). Rest of grand slam champions are under 5 since 2006 - Cilic, Nishikori, Medvedev, Thiem and Del Potro. Maybe I am missing someone - o yeah Alcaraz. Once Nadal and Djokovic are gone I will be surprised if 10 time grand slam champion emerges until 2040 and it will be the time of "great champions". As far as young kids choosing sports, they all choose few and stick with one eventually. Tennis is unique because it requires commitment from very young age, sometimes too young to choose something else.
When I talk about depth and competition, I’m not just focusing on the players competing for grand slams, in the top 10. I’m focusing on the top 100 overall (to me that’s a big deal as those are the players who qualify directly for grand slam main draws and other tour events. I watch as much ATP tennis as time permits including smaller events, and I think tournaments like Rotterdam, Estoril etc. were far more interesting in previous eras than they are currently, and the same goes for early rounds of grand slams and masters series events. There was more variety in terms of playing styles and surface conditions in previous eras (things have become more homogenised over time). I mean reverting back to that 1992 US Open, Edberg beat Krajicek, Lendl, Chang and Sampras in succession to win that tournament, 4 players with noticeably contrasting playing styles. 2 years earlier, Sampras beat Muster, Lendl, McEnroe and Agassi to win the title, again beating players with a wide range of different styles. Modern day players certainly don't have to worry about that.
Variety has massively gone out of the window, and so many players in born from the 90s onwards, play bland ‘academy style’ tennis.
And the ‘transitional period’ in the early 00s was labelled as week, but again I strongly doubt the depth in the ATP top 100 has been better in recent years than it was then. 2001 for example was a wonderful year packed full of high quality matches across the board, in tournaments at all levels on the tour.
I think that tennis for a long time was only a big deal in the 4 countries that hosted grand slams, then became more popular in other countries across the globe over time (it's popularity really exploded in the US in the 70s and the Connors, Borg, McEnroe era significantly improved it's global status). But then over time the gulf between the money on offer in teams sports and it widened to such a huge degree (in recent times most tennis players would love to earn what League One footballers are making never mind Championship footballers, and the lowest earners in the major North American sports leagues earn more than players in the lower reaches of the ATP top 100) that the appeal of tennis on the men's side began to reduce again. I honestly think that the talent pool in men's tennis has shrunk in recent times after it previously increased over time, and that professional tennis has become more elitist and restrictive. I mean challenger level players /most players outside the top 100 are financially worse off in 2023 than they were in 1993 or 2003, because the costs of playing expenses has increased at a faster rate (with inflation) than the levels of lower level prize money on offer.
Agassi didn't grow up in poverty or anything, but for the standards of men's tennis (you get far more interesting backstories in women's tennis with it being the no. 1 women's sport for such a long time) came from a reasonably blue collar background. His dad famously pushed him towards tennis, and said that if he could have done it again, he would have pushed him towards baseball or golf instead. He grew up when tennis was approaching and then at its most popular in the US.
But I still love playing and watching tennis though.