I'm not sure if MK even has, or want's, a discount brokerage business. They tend to focus on high net worth portfolios. True, they've gotten a bunch of accounts from the past mergers but most of these are for annuities and IRA's in accounts that don't do a whole lot of trading to begin with.
Also...if by 'Discount Brokerage' you are referring to the ability to conduct online trades, I've had this ability in my MK account for years. It's a nice feature but I rarely make use of it. I prefer to contact my financial advisor and have him 'check the math' on all of my investment decisions. Otherwise, I'd just open an e-trade account.
MK has an excellent in-house research/analysis team and that is one of the things that sets them apart from their competition. I pay more in commissions but my portfolio reflects the wisdom of this 'non-discount' guidance.