I'm not sure why OP thinks it is "pretentious" to charge more than he thinks is good value. Either the property is over-charging for the market and will eventually fail or it is able to get those rates and it is OP who simply does not understand the particular market. My money is on Marriott having this right as Marriott has the data.

As to group and corporate rates, those often come with features which individual rates do not. Parking, late cancellation, resort/destination fees, and the like are often waived or discounted and that can be hard to factor into value for any one individual on any one stay.