Thought I'd do a little comparison. All stats are Premier League since 1992 and First Division from 1962-92

Number of different teams that competed

Premier League: 50
First Division: 49

I must admit to being surprised at this. Some might rightly say that between 1962-73 only two sides won promotion from Div 2. However, only one of those sides never ended up playing in the First Division between 1962-92 (guess which team....)

For all bar 4 seasons, the First Division had 22 teams in it. The PL has had 38 for all bar the first two seasons. On average, each team in the First Division would have played 554 games; in the PL that drops to 466. More teams have been able to enjoy more of the PL than they did in the last 30 years of the First Division.

Champions

Premier League: 7
First Division: 9

Only Liverpool, Arsenal, Man Utd and Man City won the league in both timeframes. Blackburn, Leicester and Chelsea have won the PL but didn't win the First Division (between 1962-92), while Derby, Forest, Villa, Leeds and Everton have never (yet) won the PL.

Liverpool were the dominant side in the last 30 years of the First Division, winning 13 titles. Man Utd won the same number in the PL. Between them, the top 4 champions of the PL, Man Utd, Chelsea, Man City and Arsenal have won 26 titles (maybe 27 this season). In the old First Division, the top 4 champions, Liverpool, Everton, Arsenal and Leeds, won 23. There was a little more sharing around of the league title. I haven't looked, but I expect there was even more if you looked back another 30 years.

Top 2/Top 4 finishes

So far we can say that more teams have had a nibble at the PL than they did the First Division over its last 30 years but it has been more difficult for teams outside the big few to win the league. The advent of the Champions League and multiple places in it for the best teams in the division (plus the money awarded) has had an impact.

Between 1962-1992 14 teams finished in the top 2. For the PL that figure is 10.
Between 1962-1992 23 teams finished in the top 4. For the PL that figure is 14.

Here are the teams with the greatest number of top 4 finishes

Premier League (Liverpool, Man City and Chelsea's top 4 finish this season already included):
Man Utd - 25 (26?)
Arsenal - 21 (22?)
Liverpool - 19
Chelsea - 19
Man City - 12

Between them, the rest, Tottenham (6, 7?), Newcastle (5), Blackburn, Leeds (3), Villa (2), Norwich, Forest, Everton, Leicester (1) have appeared less in total than Man Utd have. The former glories of most of those sides happened earlier on in PL history, so the concentration of the top 4 in more recent seasons is frightening. It is certainly harder to get into the top 4 than it has ever been.

First Division (1962-92):
Liverpool: 23
Man Utd: 14
Everton: 12
Leeds: 12
Arsenal: 10
Tottenham: 9
Ipswich: 7
Forest: 6
Derby: 5
Man City: 4

You can add Villa, Burnley, Chelsea, West Brom, Leicester, Wolves, QPR, Watford, Southampton, West Ham, Norwich, Palace and Sheff Wed with 18 combined.

11 clubs have spent 20+ seasons in the PL. 18 sides spent 20+ seasons in the First Division.
28 clubs have spent less than 10 seasons in the PL. 21 clubs spent less than 10 seasons in the PL.

While it's true to say more teams have had a bite at the PL, it has certainly been harder for smaller teams to stay there. Bigger clubs, on the contrary, have found it easier to stay in the top flight. Imagine Spurs and Man Utd being relegated nowadays?