I did some math here...
If Sesame Workshop did produce season box sets, and season one came out in fall 2005 (although realistically from now that's calling it close). And they then released each subsequent season every 6-months (or 2 a year), which is normal for TV shows season set releases. Assuming that Sesame Street stays in production, we would not catch up to the current season untill the fall of 2042 (season 75), and if you bought all the seasons up to that point it would cost up $3,000.00 (assuming standard season set price of $40). Just to get to season 35 (the one right now) you take until spring 2022 and would cost $1,400.00
Even if they did 4 release a year (a season every 3 months), it would take until Spring 2017 to catch up to the current season, and would cost up to $1,800.00
Aside from the few hard core Sesame fans like us, not many would want a compleate collection of the 1969-70 episodes; being they are repetitive at time in repeating skits/songs from episode to episode and are rough compaired to today's show. $40 for a set is going to scare away the more modern and casual fans. To justify a product there would need to be a huge market for such sets to justify, I don't think compleate collections of the seasons would get a big enough market.
Now, if they did "The Best of" collections for each 5 years pf the show they not only would be a lot cheaper; but faster too. If each was 2-4 hours of pure classic Sesame footage (they even could toss in bonus features), they would most likely retail for $20 each (based on standard retail price for disk of that quantity of material) the 7 needed to get to today (8 to catch up to the future seasons). Below is a list of how they could be released.
The Best of 1969-1974 (Fall 2005)
The Best of 1975-1979 (Spring 2006)
The Best of 1980-1984 (Fall 2006)
The Best of 1985-1989 (Spring 2007)
The Best of 1990-1994 (Fall 2007)
The Best of 1995-1999 (Spring 2008)
The Best of 2000-2004 (Fall 2008)
The Best of 2005-2009 (Spring 2009)
It would take less than 5-years to catch up to today, and could total less than $160