Check this post, but I don’t think that’s your problem. Boosting destructive nodes tends to produce to much unwanted noise.
Getting a flat frequency response will make the sound more focused and narrow, which if you are used to the opposite will make it feel like you get less body and life. Try listening to it for a day or two, and then switch back and compare.
If you still don’t like the room corrected sound, you can limit the correction to where its needed most (usually lower frequencies), for example 20 - 500 Hz. You can also tell REW to have a higher tolerance by changing the Flatness target in the EQ window before generating the filter (for example, setting it to 5 dB will make REW only correct those places with a >5 dB difference).