The current eligibilty rules are fine IMHO.
I believe that a player who is born in a country should play for that country, or at least have the choice. However, if they then move abroad and become a naturalised citizen then as long as they have not decided to play for their birth nation at a senior level, then they should be allowed to play for the adopted country where they reside and settled.
I would say that it should be taken to the higher age groups also, like U19. If you are capped at age-group, you must play for their senior team only, if selected.
The 7's rules need to be kept very tight as New Zealand will cap potential Manu Samoa, Fiji and Tonga senior players living in NZ with no intention of capping them for the All Blacks, just so they cannot play against them if they do make an island team. I think this is the only point to be argued.. but of course, they DO have a choice to play for NZ or not.
The politics between Samoa and New Zealand for example, is quite complex and transcends sport completely. Samoa is a very small, third world country and the history between NZ and Samoa goes back to the end of WW1, when New Zealand took over control of Western Samoa unopposed from the Germans (who had it previously) all the way up until 1962, when Samoa declared it's independence from NZ.
Apart from two major incidents, New Zealand has generally been positive for the development of Samoa and it's people to give them an opportunity to live in New Zealand, where they can make something much better of their lives than they ever could in Samoa, and that includes both the Rugby codes. In fact, Manu Samoa Ltd is bankrolled by a kiwi. The only argument for NZ not giving back to Samoa is with test matches.
So, naturally now there are many Samoans living in NZ who have no formal connection to Samoa other than being of samoan descent. All the guys on this forum are of that group i would guess. They are kiwis, but acknowledge the culture of which they descend from, but have no direct link.
So, it works both ways. If you was only allowed to play in the country of birth, then Samoa could have fielded:
Va'iaga Tuigamala, Jerry Collins, Alama Ieremia, Chris Masoe, Mils Muliaina, Isaia Toeava, Casey Laulala and Rodney So'oialo as they was ALL definitely born in Samoa.
Likewise, Fiji can field Sivivatu and Rokocoko.
But you'd have to remove the NZ-born (or other born players) who'd include: Lome Fa'atau, Pat Lam, Seilala Mapusua, Sailosi Tagicakibau (Fiji), Stephen Bachop, Earl Va'a, Frank Bunce, Gavin Williams, Peter Fatialofa and Apollo Perelini.. who were all born in NZ and we all know these players formed the winningest sides in Samoan rugby history.
In fact, if it wasn't for the current rules, then Samoa would be in a much poorer position in World Rugby. At the RWC 2007, Manu Samoa fielded 14 New Zealand-born players compared to just five Samoan-born players in the All Blacks squad. That tells it's own story. Those players have become stars because of New Zealand, not anything remarkable (training wise) that Samoa has done.
All these All Blacks are born in places like Apia, and Moto'otua, but they moved to NZ at an early age and grew up there, learned all their education and rugby there in the main, but have that key samoan ingredient. Samoa has no claim to them as such and technically THEY are poaching from NZ to fill ranks in Manu Samoa.
Ask any young aspiring samoan rugby player living in Samoa who they want to play for, and they will almost say the All Blacks, every single time. This is because every young samoan male rugby player dreams of being an All Black and following the footsteps of their icons.. Muliaina, Collins, Masoe and so forth. Also the money factor.
Although in the tiny villages, like Fagaloa where my in-laws live.. they will follow the most famous nearest local player, in Fagaloa's case it is Mikaele Pesamino from Vailele.
This is very good for the future of Samoan rugby as Pesamino is a Samoan 7's cap and hopefully will gain full caps in 15's for Manu Samoa, whilst playing in NZ with Auckland in NPC.. rather than choosing to play for NZ.
The top players that end up playing for Manu Samoa, such as David Lemi and Alesana Tuilagi are not playing because they want to play for Samoa firstly, it's because they can't play for the All Blacks. This is by far no detriment to Samoan rugby.. i have seen first hand exactly how they enjoy this game and how religious they are about it and it means everything to them. It's just the way in a poor country to go after the money.
What it means is that now more and more samoan players are earning great money in professional teams in Europe and Japan, they will choose Samoa for the right reason, which is because of birth and the fa'a samoa.