I wouldn't buy 'high-end' anything (law of diminishing returns) but a few things to consider that nobody has really touched on yet:
You have to separate audio and video issues.
Audio
If you use a digital audio connection from the player to the receiver then most, if not all, of the audio processing features of the player are moot. But, IMO that is what you should prefer anyway. The receiver is the brains of the operation and once it has the audio in a data format (instead of analog) it can manipulate it untold ways - apply time alignment, xover, tone/EQ controls, re-EQ, cinema filter, late night mode (dynamic compression), matrix decoders, and on and on ad nauseum. So for audio with a digital connection, I'd say yes a high end player is redundant and not worth the cash outlay.
Video
Video is a whole 'nother ball game. DVD is a standard but standards docs have a whole lot of may and should in contrast to must (I work with software standards). Therefore there is a lot of leeway, not to mention that authors don't always follow the rules anyway (either on purpose or out of ignorance). Just like software, if something becomes popular and is in wide use, despite not technically following the letter of the law, the code must be changed to support it because nobody wants their code to not support the most popular application on the planet.
This is where high end players come into play. They can deal much better with the zillions of combinations. Video processing algorithms are more complex than audio and that is what you are paying for in a high end player. Receivers are starting to incorporate deinterlacing and scaling algorithms but that pales by comparison to decoding and things like locking onto the cadence when things change from video to film and back again. You'd want a better player to deal with all that junk if you are extremely picky about video and/or have such a wide selection of source material that a large number of the potential problems exist in your collection.
However, I still think the point is somewhat moot there too as many lower cost players (think Oppo) have been shown to do what the big expensive boys can do and yet at a fraction of the cost.
I'd put my money into the processing chain (pre-pro/receiver) and not so much into the player...but that is just my opinion. A 1K receiver with a $200 DVD player is a perfectly acceptable combo as far as I am concerned.