Often the design requirements for artistic reasons are diametrically opposed to industry standard requirements (for example for RF emissions and/or immunity). KiCad is targeted to the industry requirements so any artistic considerations are only secondary if even considered at all.
Unfortunately, this will have to be true. But it is important to know which DRC rules you are violating intentionally (for your artistic license) so you can pay proper attention to the ones that must remain inviolate (like manufacturing minimum trace widths and clearances or circuitry issues).
Unfortunately, that is like wanting a grammar checker to be improved to accept poetic (or dialectal) grammar for that novel your are writing where your artistic choices to break grammar rules really only apply to the work you are creating.
That said… There are actually times in circuit design where floating islands of unconnected copper is acceptable (for example flex circuits). Other features that are specific to flex circuits (gridded planes) may be coming in the future so there might be hope that floating copper islands might be included.