<font face="Verdana, Arial, Helvetica, sans-serif" size="2">Originally posted by santo:
NW reservations do have the option to see all your reservations in one page, you can change seats after reservations etc etc. Spend a little more time, you'll get used to it.</font>
This only applies to reservations made through nwa.com (in terms of seeing all reservations and being able to change seats online).
delta.com allows the user to see any reservation that has the user's Delta SkyMiles number.
That's a huge difference.