While all you're saying is undeniably true, it's also undeniably true that using Joan 2.0 with her spitfire in active turn with that sweet sweet B5 BS21 (before negative mods) is ultimately satisfying. What I did a couple of times to make the Crusader fireteam more manageable is to split it in a Hospitaller Haris and a Duo with Joan and a Santiago, usually the KHD version. This way both fireteams can do their own thing, and if they eventually meet up somewhere on the table later in the game, they can go Crusader. Of course, you have to keep all your knights alive up to that point, but it can be done. And if you can't, well at least you didn't have a Crusader Fireteam to start with.
On top of that there's the fact that you can't add a spec sergrant to cut down on costs. To be entirely honest I don't rate Joan that highly in MO at all - there aren't enough irregular troopers to take advantage of inspiring leadership with, and you'll have links so the free coordinated order is significantly less valuable. I'd much rather just take a regular hospitaller team with an HMG.
You can do some interesting things with Joan, but they are certainly not Knight-heavy Core builds. Military Orders ────────────────────────────────────────────────── GROUP 1 10 3 JOAN OF ARC Lieutenant Spitfire, Nanopulser / Pistol, AP CCW. (1 | 51) MAGISTER KNIGHT Panzerfaust, Light Shotgun / Pistol, DA CCW. (0 | 23) MAGISTER KNIGHT Panzerfaust, Light Shotgun / Pistol, DA CCW. (0 | 23) MAGISTER KNIGHT Panzerfaust, Light Shotgun / Pistol, DA CCW. (0 | 23) ORDER SERGEANT MULTI Sniper Rifle / Pistol, Knife. (1.5 | 21) ORDER SERGEANT Heavy Rocket Launcher / Assault Pistol, Knife. (1.5 | 15) ORDER SERGEANT Heavy Rocket Launcher / Assault Pistol, Knife. (1.5 | 15) ORDER SERGEANT Paramedic (MediKit) Combi Rifle / Pistol, Knife. (0 | 15) ORDER SERGEANT Combi Rifle / Pistol, Knife. (0 | 13) ORDER SERGEANT Combi Rifle / Pistol, Knife. (0 | 13) GROUP 2 5 2 TECH-BEE (Remote Assistant Level 1, Specialist Operative) Flash Pulse / Pistol, Knife. (0 | 5) WARCOR (Sixth Sense L1) Flash Pulse / Stun Pistol, Knife. (0 | 3) MACHINIST (Father-Engineer) Combi Rifle, D-Charges / Pistol, Knife. (0 | 15) PALBOT Electric Pulse. (0 | 3) TRAUMA-DOC (Father-Doctor) Combi Rifle / Pistol, Knife. (0 | 14) PALBOT Electric Pulse. (0 | 3) SPEC. SERGEANT Hacker (Hacking Device) Combi Rifle / Pistol, Knife. (0.5 | 21) PATHFINDER DRONBOT Combi Rifle, Sniffer / Electric Pulse. (0 | 16) FUGAZI DRONBOT Flash Pulse, Sniffer / Electric Pulse. (0 | 8) 6 SWC | 300 Points Open in Infinity Army
At 400 pts, you can field Auxbots OS, Sierras and all those support and defensive units good to make your DZ hard to break in. This FT is like a super TAG your opponent can't possess but he can wreck it into pieces if you make too much mistakes. But you can still hit the 18 orders with it without much effort. I think I would prefer DeFersen in it instead of Joan though but that's an other question.