When installing thunderbird, I would like to be asked if I want to install the calendar option.
I don´t need the calendar option as I use a paper one, and therefore don´t want to have the calendar option as a part of thunderbird. Thunderbrid was once a plain mail client and I think it should stick to that. Those who want a calendar option can set their mark on an option to include it.
I like gimp. There I can choose to not install different plugins I don´t use anyway, this making my complete installation of gimp thin and not so memory or file hungry.