The Achilles heel of many Chromebooks is poor matte finishing on sub-standard LCD TN panels (the Acer C720 is a good example of this). Most of these panels strain the eyes; something accentuated with a matte finish that mutes colours, brightness and generates a foggy like haze effect over the display (I am specifically pointing out Asus and Acer as the main culprits in producing sub-standard displays). I would not say this is predominantly an issue of preference between glossy or matte but the use of sub-standard panels with a lack of care when applying a matte finish (e.g. the anti-glare used on the HP Chromebook 14 is better than what Acer and Asus offer).
(1) The Dell 13 Chromebook's flexible choice in configuration would be something different. However, I would classify the Dell 13 Chromebook as tilting to the premium than mid-range, due to its build quality and needless extras (e.g. back-lit keyboard); Dell also market this as a 'business class' Chromebook, rather than a general consumer product. The ideal Chromebook, something that manufacturers oddly neglect, would be of similar build quality to existing Chromebooks but with a good IPS display and good enough performance.