Is it legal to install msttcorefonts package? Is Wine legal?
msttcorefonts is considered globally legal for installation because the license for the fonts allow them to be installed and by omission, installed on non-Windows operating systems, without a Windows license.
In short: It's not a case of copyright law because Microsoft allows the redistribution of the font installers and it allows users to install the fonts (regardless of OS).
It does not allow for redistribution of the TTF font files on their own, so, for example, it would not allow for a distribution like Ubuntu to include them by default.
Sidebar: The newer (Vista-era) fonts like Consolas, Segoe, Cambria, Candara have explicit "only for Windows" junk in their licenses, but these fonts aren't included in msttcorefonts so that doesn't matter.
Wine is less black and white.
From a copyright stance, great effort seems to go into making sure that all of the Wine code is completely original (eg people who have seen Windows code are not allowed to contribute) and that helps to keep the copyright side of things fairly clean.
But technology wise, it's aim is essentially to redevelop the core of Windows. I'd be surprised if there weren't more than a couple of Microsoft patents it trod on. Microsoft has been filing patents for every other line of code for 20 years and the USPTO has been more than willing to grant them all sorts of silly, super-obvious patents.
Anyway, this shouldn't affect you directly (yet) because there hasn't been any legal action (AFAIK) and even if there were, it would be likely to happen in the US. I'm not a lawyer so I can't say how this would affect you either.
If you need a bullet-proof legal way to run a Windows application from within Ubuntu, virtualisation is probably the key. A real licensed copy of Windows running will do almost anything you want it to (with a performance hit).
I am not a lawyer, but generally speaking packages that are included in the official Ubuntu repositories are not encumbered by any copyright or patent restrictions that would make it a tort or crime to install. A number of useful packages are excluded from the official software sources because it would be unlawful for some users in some places to install them, due to such concerns. One example of such a package is libdvdcss2, which is provided in the unofficial Medibuntu repository. By enabling unofficial repositories and installing packages where you've been warned of possible copyright or patent issues, a user takes full responsibility for determining the legal status of their actions.
However, while msttcorefonts is provided in official Ubuntu software sources, is not free open source software. This package installs proprietary fonts copyrighted by Microsoft. When you install it, you are asked agree to Microsoft's terms of use for these fonts. You would probably incur civil liability if you installed this package and then engaged in acts covered by the copyright laws in your jurisdiction and prohibited by the terms of use.