Before you go run off and type up that one feature you've always wanted, here's some questions you should address (as applicable) in your feature suggestion to make it stand out and be more likely to be implemented into the addon. If you don't have good answers for these questions, your suggestion likely needs to be flushed out more first.
The suggestion has been added to the system and it's open for everybody to see. All feature suggestions start in this state and will likely remain in this state for a considerable amount of time. Other people can now vote for the suggestion to show their approval and/or discuss it via comments. Developers may comment to request additional information, provide some context, or otherwise guide the suggestion in the right direction. If there is enough support for the feature, and the developers feel it would make a good addition to the addon, it will move into the "planned" stage. If the developers decide that it would not make a good addition to the addon (rare), or there is something wrong with your suggestion (much more common), it will be moved to the "Declined" stage.
Your feature suggestion was awesome! It has gained enough support that the developers have decided to add it to the addon. At this point, a developer will likely add a comment with a rough time frame for when the feature will be added, but you can safely assume it won't be too long before your very own feature becomes part of TSM.
The suggestion has been incorporated into the addon. This is the best possible outcome for a feature suggestion and you rock for getting it this far.
If your suggestion is not a valid suggestion for any reason (perhaps it's already implemented, not possible, or incomplete) or the developers decide that it will not be added to the addon, it will go from the "No Status" phase to this phase. Do not re-post your suggestion if it's marked as declined unless instructed to do so by a developer. A developer will leave a comment on the ticket explaining why it's been marked as declined.
So, how do the developers decide what suggestions will be implemented in the addon? There are many things to consider. A few of the important ones are detailed below in no particular order.
The current feature suggestion system allows users (and developers) to vote on suggestions they like and want to see added to the addon. The developers will use the number of votes as an indicator of how many people would use the feature. Nothing more, and nothing less. This does not diminish the importance of votes, but keep in mind that they are only one part of the process. Just because a suggestion has the most votes doesn't mean it will be added right away. However, it's very likely that suggestions with lots of votes will also meet the other criteria and eventually be implemented.
It's very important to avoid (and remove) unnecessary features which are only used by a small percentage of the total user-base. This keeps the code and the user experience as simple as possible. Adding additional options or frames to the addon creates some level of visual noise and confusion, and it's important that this is fully justified by the usefulness of the feature. This is one of the primary reasons features are not added to the addon.
Of course, every new feature will take some amount of a developer's time to implement into the addon. Whether or not it's worth the development time is also taken into consideration when evaluating a feature. While it may seem trivial to add a new option, for example, there may be other aspects of the code which will be impacted by the suggestion which would also take development time.
As explained more in the previous section, logging in with multiple different emails in order to add votes is pointless and will not help your suggestion. It's very easy to spot such abuse and excessive abuse may lead to your IP being banned and your suggestions/votes being removed, which is really not helpful to anybody. So, just don't do it.