I'm saying that bitcoin is going to 'jump out of the window' and hurt itself if we encourage closed-source implementations
Do you have the impression that one or more individuals within our community that may indicate, suggest or to have admitted to use a proprietary closed source Bitcoin-related application is indicative that "we encourage closed-source implementations?" Who is "we?" Is "we" a kind of central authoritative figure? I think there will be individuals that pursue their own decisions, choices that may conflict with others, however, it should not be considered that if one or more individuals share the same or similar decision or choice, even if such decision or choice is majority, that "we" as a community are representative of that choice.
I think there may be confusion being generated about this topic. Perhaps a poll can help to provide a better understanding as to how others feel about using proprietary clients. However, again..
Even if we think it is always best to use an open source client, there are still circumstances when the MIT license would be a valid choice.
One of the characteristics of the MIT license is t it is compatible with most other licenses. That way, you can write a new client which combines the MIT-licensed code with code that is under some other kind of license.
Perhaps this will enable someone to write an open source client that combines parts of the existing implementation with existing GUI libraries, database frameworks, logging utilities, etc etc.
The flexibility of the MIT license is a big help if you want to encourage the adoption of niche software.
That is a good point that should be reiterated for these types of discussions.
For example, if Microsoft, Sony, Nintendo, Apple, etc. were to show acceptance of Bitcoin but release a proprietary version that is integrated within their product (e.g. proprietary implementation integrated into ps3/ps4, just like all the other proprietariness within), there is no point in arguing against Sony's actions. Arguing about it is pointless. In the case of Sony designing their own proprietary implementation integrated into their hardware, there most likely will also be an initiative to hack the system and to provide an open source implementation anyway, and for those that are geek enough, they will probably use the open source version instead. For those that just want things to work (majority, mostly computer-illiterate and prefer to consume time pursuing other activities anyway), then they will use proprietary version.
In the case of Bitcoin, the open source version is currently the dominant version. It is the most recognized or the first noticed. As far as I can tell, proprietary versions of Bitcoin haven't been advertised to the masses more so than the official open source Bitcoin client, so although there is discussion about the particular version, it isn't taking over or becoming more popular than open source version.
It is probably most productive and best for the community overall for those advocating open source and against proprietary to learn how to program (if not already familiar), rather than arguing for it whilst expecting everyone else to develop/program open source alternative. While it can be argued that one is not a developer or doesn't have necessary skill, perhaps that is just a sign of laziness or unwillingness to stand up for one's beliefs. It would be more reputable, admirable if one were to pursue their argument by contributing towards development to support their argument.
On a side note, Macho, is that you in my profile picture? *chuckle*