Some people think too many teams make the playoffs these days.
Right now, 53.3% of the league makes the playoffs (16 of 30 teams).
Here are the NBA all-time playoff formats ranked by the percentage
of the league that went to the post season. "7 of 8" means that 7
of the 8 teams in the league that year made the playoffs. The other
numbers are the number of years the league used that format, the
percentage of teams in the league that made the playoffs, and the
rounded off number of today's 30 teams that would make the playoffs
under that format. The two years that 7 of 8 teams made the playoffs
involved a tie-breaker game. So the 53.3% of today's league that
makes the playoffs is a fairly small number.

  Teams     Years    %      # Now
7  of  8     2     87.5%     26
8  of 10     4     80.0%     24
6  of  8     6     75.0%     23
8  of 11     1     72.7%     22
12 of 17     1     70.6%     21
16 of 23     5     69.6%     21
8  of 12     1     66.7%     20
6  of  9     6     66.7%     20
16 of 25     1     64.0%     19
16 of 27     6     59.3%     18
8  of 14     2     57.1%     17
16 of 29     9     55.2%     17
12 of 22     4     54.5%     16
6  of 11     1     54.5%     16
12 of 23     3     52.2%     16
8  of 17     4     47.1%     14
8  of 18     2     44.4%     13

Since there were only two divisions under many of these formats,
the team's place within it's division was used for seeding, so
some really bad teams made it. Here are the worst teams ever to
make the NBA playoffs, with the number of teams making the 
playoffs that year in parenthesis:

1953 Baltimore Bullets (8 of 10)   16-54  .229  lost playoff 2-0
     This team also has the 46th worst record of all time
1960 Minneapolis Lakers (6 of 8)   25-50  .333  beat Detroit 2-0 *
     then lost 4-3 to the 46-29 St. Louis Hawks, who
     lost the championship series to the Celtics 4-3
1968 Chicago Bulls (8 of 10)       29-53  .354  lost playoff 4-1
1950 Sheboygan Redskins (12 of 17) 22-40  .355  lost playoff 2-1
1986 Chicago Bulls (16 of 23)      30-52  .366  lost playoff 3-0
1988 San Antonio Spurs (16 of 23)  31-51  .378  lost playoff 3-0
1950 Phila. Warriors (12 of 17)    26-42  .382  lost playoff 2-0
1959 Detroit Pistons (6 of 8)      28-44  .389  lost playoff 2-1
1960 Detroit Pistons (6 of 8)      30-45  .400  lost playoff 2-0 *
1955 Rochester Royals (6 of 8)     29-43  .403  lost playoff 2-1
1967 Chicago Bulls (8 of 10)       33-48  .407  lost playoff 3-0
* The worst two playoff teams in 1960 met eachother