Explant, no capsule removal. Why do some doctors take them out and others don't?

Thank you for the good question.  Generally speaking,  if the breasts and the underlying  breast implants feel soft (to deep palpation) and the breast implants seem to move freely (not fixed for firm), then it is very likely that the capsules are thin/normal. 
 Some general thoughts regarding this issue may be helpful to you: generally speaking (in my opinion), unless the breast implant capsules have thickened (and/or are otherwise symptomatic),  are associated with the ruptured silicone gel breast implants, or if the patient has concerns about "medical conditions" related to the breast implants, capsulectomy is not universally necessary.  For these patients, en block removal of breast implants is a good procedure.
On the contrary, capsulectomy can expose you to additional risks, such as bleeding and minimal size loss.  In other words, any maneuver performed during surgery exposes patients to additional risk (morbidity).
 Recently I have  become more aware of the fact that there are plastic surgeons who, instead of using good judgment and individualized patient care, are causing fear and unnecessary anxiety among patients. These patients them feel that complete capsulectomy is always necessary and undergo unnecessary surgery  associated with additional morbidity and unnecessary expenses.
 I hope this, and the attached link, helps. Best wishes for an outcome that you will be very pleased with.

When you decide to remove your implants there are other decisions to be made as well. If your capsules are thickened, causing issues, or if your implant is ruptured generally it is recommended that you have your capsules removed with the implants. If your capsules are thin and not causing any concerns then you can elect to have them removed or leave them behind. Your surgeon will also want to discuss if you are interested in having a lift to reshape the breasts, or perhaps exchanging your implants for a different size or style. I've included a video that I hope you find helpful.

If the implants have leaked silicone, the capsules should probably be removed.  Find an expert in your area who has great reviews and before and after pictures.Kenneth Hughes, MD, Board Certified Plastic Surgeon
Los Angeles, CA