You are absolutely correct and if you listen to the DVD through your TV, then in most cases there's no real solution (except the sub les, obviously). If you use a surround receiver most have a "night mode" button/setting, that will actually enhance the dialogues and dampen the FX (most noticeably the sub-woofer).
This has annoyed me for years, since there's enough space on the discs to simply add a normal stereo audio mix without the FXs and allow this choice for the viewer. This used to be the norm in early DVDs, but nowadays is quite rare.