The two person rule is more practical for some aircraft types/cabin set ups than others. If it works for you then you are clearly not facing the issues some of us are.
Ignoring the security element of it for one minute (i.e. you now introduce MORE predictability as to when a door is going to open. I.e. If a CC member has gone into the FD, rest assured a pilot is going to come out within 30 seconds and vice versa), it's damn awful not to be able to have a pee when I choose. Instead someone else decides. We fly fully laden 220 passenger A321s with average sector length at 4 hours, with only one toilet forward of row 19.
Everybody from that row onwards and a good portion of those behind row 19 want to use toilet number 1 (lack of education on this also pisses me off). As such, timing is of paramount importance. We used to be able to look at the camera screen, see the area is clear and jump out for a pee. Not now, by the time you've got the attention of a CC, they have come in and you get up, there could be 2 or 3 people standing in the forward galley. If it's a granny or a little kid, you think twice about asking if you can go in first. It's not a healthy setup, especially if like me you pee as often as a water fountain at altitude (I'm fine on the ground). Whatever timing you had in mind when you were sitting and and thinking of a pee, is now gone through the window. Now you're standing and holding it. Yes, we are not children - we should be able to hold it! But holding it 3 or 4 times a day for longer than I would if I were on the ground, AND for the rest of my flying career? That's got to be doing some long lasting damage!
Yes, my airline doesn't curtain off the forward galley or station a cart in between. It considers it too impractical.