In other words, "wishy-washy."

nothing worng with previous answers but you specifically asked about "-ese"

http://www.thefreedictionary.com/ESE

"translationese" would be a good example of how the -ese part adds a disparaging effect

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Note added at 17 mins (2013-11-26 16:50:44 GMT)
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typo: wrong!

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Note added at 17 mins (2013-11-26 16:51:05 GMT)
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a suffix forming adjectival derivatives of place names, esp. countries or cities, frequently used nominally to denote the inhabitants of the place or their language (Faroese; Japanese; Viennese); also occurring in coinages that denote in a disparaging, often facetious way a characteristic jargon, style, or accent: Brooklynese; journalese.

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Note added at 19 mins (2013-11-26 16:53:24 GMT)
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http://www.merriam-webster.com/dictionary/-ese

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Note added at 1 hr (2013-11-26 18:09:48 GMT)
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Here, of course, it's the "coinage" part of the definition above and it usually adds a "disparaging, often facetious" tone for the "characteristic jargon, style, or accent: Brooklynese; journalese".

It will depend on the context, but in principle this should refer not to the paper's attitude (which would simply be "middle-of-the-road") but to the kind of language it uses. As well as being used to form a number of nationalities or languages, such as Chinese from China (the result of which can be either a noun or an adjective), the suffix -ese can also be added to some root to denote a kind of jargon, by analogy with a language like Chinese, the result of which is a noun:

"Suffix
-ese
- Used to form adjectives and nouns describing things and characteristics of a city, region, or country, such as the people and the language spoken by these people.
Viennese, Maltese falcon, Parmese, Japanese, Faroese, Viennese waltz
- Used to form nouns meaning the jargon used by a particular profession or in a particular context.
journalese, legalese, translationese"
http://en.wiktionary.org/wiki/-ese

Your term, coined by the writer, belongs to the second category: "middle-of-the-road-ese" means the kind of language characteristic of middle-of-the-road people: unadventurous, non-committal, avoiding extremes, just as journalese is language characteristic of journalists.

The effect is humorous, and this use of "-ese" to refer to a type of language is pejorative.

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Note added at 23 mins (2013-11-26 16:56:43 GMT)
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So the journalists working for a middle-of-the-road paper write in "middle-of-the-road-ese": safe, moderate language, avoiding extreme or challenging statements. This way of expressing it makes it sound negative.

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Note added at 15 hrs (2013-11-27 07:37:59 GMT)
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Danya's comment is incorrect. "Middle-of-the-road-ese", as I have explained is a noun, not an adjective, and can only refer to a type of language. That is, assuming that the suffix has been used correctly.

Despite what he says, the context we have been given does not show that it refers to the paper itself. "Its middle-of-the-road-ese" is quite obviously a noun, unless you have failed to include a following noun (for example "its middle-of-the-road-ese" editorial policy"). I have assumed that is not so, because I am sure that if there were a noun after this you would have included it. But if there is, the "-ese" suffix has been misused. The writer would simply have said "its middle-of-the-road editorial policy", or use another suffix, such as "its middle-of-the-road-esque editorial policy".

As it stands, this is obviously a noun. And as all the references and examples posted here show, words like this always refer specifically to a type of language, not an attitude.

I have emphasised this because it seems to me that although you need to know that "-ese" is a suffix, you also need to know the exact meaning of the word constructed with it. When I posted my answer, no one had addressed that point.

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Note added at 15 hrs (2013-11-27 07:48:08 GMT)
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All the examples of this use of the suffix "-ese" that have been given here refer to types of language and to nothing else: Jack's "PR-ese, Human relations-ese, bureaucratese", gallagy's "Brooklynese; journalese" and my "journalese, legalese, translationese".

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Note added at 15 hrs (2013-11-27 07:50:43 GMT)
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"Translationese", for example, means "the characteristics of language that manifest themselves more abundantly in translated text as opposed to a text generated natively in that language"
http://fluencytranslation.blogspot.com.es/2011/12/translatio...